Juggular

I also second Sport Tuned, it's always a safe choice. (Sport Tuned is my go-to upgrade even after 3 dozen builds.) Here is a list of RPMs: Silver can: 14,000 Torque Tuned: 16,000 Sport Tuned : 18,500 Super Stock :26,000 (however, I'd recommend using lower gearing to keep the RPM alive--which means it will never really run at 26,000.) Above are bench tests. All brushed motors would lose about 20-30% of RPM depending on the weight of the chassis and gearing. [For future projects] 13.5t Brushless: about 20,000 - 22,000. (But you can use a taller gear ratio. Brushless would lose only about 10% of RPM due to stronger torque--which means it would run similar to Super Stock without running hot and also using less juice.) If you choose to go with Super Stock, you might consider ball bearings. RPM increase is small (about 500 RPM). However, it uses a lot less electricity (longer runtime). And it would stay cooler. Amp draw would go down noticeably. (Something like 1.8A down to 1.2A if I remember correctly). Super Stock's longevity could be shorter with brass bushings (the faster the motor, the more the axle would wear). But not when you install bearings. (@ChrisRx718 had linked this video about 3 years ago.)

Also, ample torque means 19T pinion isn't a problem at all. My guess is that even with a 19t pinion, a brushless would run cool.

I'd go with a brushless. If you said, "slow" or even "sloow," I may have recommended Sport Tuned, which is about 30% improvement. But since you added "ooo" in "sloooow," you might as well go with a brushless. If you have a Tamiya dual ESC, you only need to get a 13.5t motor for about $50 which is about the price of Super Stock. The RPM isn't better than Super Stock. However, it has ample torque. If you use a taller gearing, it can go just as fast, if not faster than Super Stock. You'd want to use a steel pinion though. Also you'd lose a lot of oomph if you use Tamiya connectors. If you want speed in any motor, you might want to upgrade to XT60 or Deans. [Torque Tuned (15% improvement) is a sales gimmick in my opinion. I would never use it, unless a used RC car comes with it.]

Tamiya includes foams for M-06 tires. I don't use them. They make the tires too hard. I want them work like real tires, not like rubber bands on plastic rims.

Thank you, I've built about 40 kits. Probably some 800 bearings. A dollar a piece would be $800. I've been lucky enough to find 10-25 cent bearings over the years, saving me $600. I'd rather buy 2 more kits with that money. So discovering places where they sell cheap is quite valuable, literally.

So that's where cheap ebay sellers went to. About 50 cents per piece isn't too bad. Tamiya's own metal bearing sets tend to be about $1 a piece (they are not even rubber-shielded). Have you found any bearing that didn't roll smoothly? I have seen stuck-in-lard bearings even in a $2-per-piece batch from elsewhere. I have 3-4 unbuilt kits (Dynahead should take some thirty 1150s by itself). My stash has enough for 2-3 kits, but I would definitely need more.

You know that moment between awake and asleep? At that moment, I remembered that I have an unbuilt XV01 (body painted), untouched Dynahead and CC-02. Dread seeped into my dream. 1) I felt guilty to have kits remaining in the box. (While there is nothing wrong with keeping things new in the box, I don't think that's me). These are kits I really wanted too. 2) Then I felt funky about a couple of static kits. I've got lots of them. For some reason, my excitement was lukewarm recently. That fact has been bothering me. These are fine kits. I should have been much more thrilled. (Though, my wife said she loves the fictional livery below) 3) I neglected listening to audiobooks (Star Wars Alphabet Squadron) I borrowed from the library. I shouldn't feel pressured by it. What difference would it make if I don't finish it? 4) I meant to sketch at least twice a week, and I have been doing only 1 a week, or 2 a month. 5) And a 3rd party Fiat 500 Abarth body... I should have kept the sticker rolled in the rubber band. But I undid the band, the sticker got unwound, and the backing came off. I should have just put it on right away. But I left it for a couple of years. Just masking & painting red tiles on the roof would be actually better when I drive it upside down. Still, that sticker (probably gone bad) has been eating me up. (But confessing the sin did relieve some guilt.) Are plans ruining the fun out of things? It's a hobby! All these are something you do at your leisure. No one is expecting me to do anything. Yet, I feel like if I don't do them as I planned, some poor puppy would be abandoned somewhere. One other dreadful thing is that I've hit 50. My insurance covers shingles vaccine when you turn 50, so I got the first shot. (My dad is still suffering from it after 16 months.) I got colonoscopy, a benign growth was removed. Unrelated to that, I gained like 5 pounds. 168 pounds for 5'8" (76kg for 173cm) still isn't terrible, but I feel a bit sluggish. All these things must have been weighing me down. And each day feels a bit shorter than one before. Am I turning into one of those old guys who's got many kits that won't be built? So it occurred to me... I should live without plans! I could do whatever I feel like, whenever I feel like. (Obviously, that'd be a no-no for any job.) But for hobbies, I think I should go with my lizard brain. Who cares if I let the CC02 rot for 10 years? (I won't.) Who cares if I don't feel excited about static kits for now. The library wouldn't scold me for not finishing a silly Star Wars book (would they?). For any occupation, 2 things are necessary: being thorough and reliable. But when I'm off the clock, I don't need to be meticulous and reliable. I should learn to let the lizard take over. I rambled on, as usual... But it had occurred to me that there are other people like me. Retraining my brain to be reptilian won't be easy. I'm easy-going to others, but I've never been loosey-goosey myself. Just thinking that I could be sloppy and free made me feel better. I'll be a human in the morning, and a slithering reptile in the evening. (I could scare my wife from the ceiling metamorphizing... wait, would that make me an insect?) We should all do whatever floats our boats whenever we want, without feeling pressured. Keep your lizard brain happy! (as long as it hurts no one)

Not exactly rubber, but I thought of a leather-pants dude I saw on an A.I. site the other day. I'm sure the horse's name is KITT. Then I thought "it could be an obsession with rubber balls." (why..?) Of course, it's about burning tires. If it's the 3rd thing that comes to my mind, I failed miserably at being a car guy...

Beta Max died that way. Beta was more compact than VHS, but didn't let others use it. So the world moved on with larger VHS. Beta died. Other people using a trade mark is a big no-no, though. Tamiya would (and should) go after 3rd party claiming to be "genuine Tamiya." Half the fun is upgrading. Tamiya seems to understand letting 3rd parties make parts is good for business. Traxxas is basically helping Tamiya expand the market share.

I've only installed spark plugs a couple times and distributor cap and coil pack once each. Looking up, dielectric grease and heatsink are both non-conductive. It dawned on me just now that the dielectric grease is to contain the spark in. It's to insulate so the spark wouldn't fly out. Wow... sometimes I amaze myself with my own ignorance! Anyway, I suppose it depends on what the focus is? Preventing the electricity from jumping out, dielectric grease. Letting the heat go through? Heatsink grease (most are non-conductive, but there are conductive grease also).

For me, experimenting is half the fun. When you get the new chassis, there is an option of using machine screws on half, self tapping screws on the other half. If cracks develop everywhere, it must be something else. (Hopefully nothing like ozone, which is bad for health) Cracks all over like that is relatively rare to see. I would be careful not to overtighten. From personal experience, hearing "Crack!" while having fun building felt like dropping a baby. "Nooooo~~!!" Hopefully, you'd have a better luck with the new chassis (who knows, you might have gotten an extra brittle chassis before. The factory might have run out of pliable pellets or something).

Ouch, I feel you. I cracked my re-issued Blackfoot chassis just like that. But I did use a big screw driver for a small screw. Too much torque. I do suspect the plastic has gotten a bit more brittle than before because I didn't have that problem with older ORV chassis from the 80s. My MF01X doesn't have any crack, however. (Then again, I did not subject it to any stress. All screws are stock.) The problem might be machine screws. (Below are M3 self-tapping screw and M3 machine screw. I think both are Tamiya.) My cheap caliper says that the shanks (the rod part) are 2.1mm vs 2.3mm. This makes sense. Self-tapping screws have to have skinner shanks. The material dug out by the thread would deform and come out to make it fit tighter. We've all seen the plastic dust on screws. That's about 10% difference. On machine screws, the threads are twice as many at given length. Since they are not supposed to dig as they go in, the shank can be fatter. No need for extra room for dust. So the shank is 10% fatter, the thread is twice as much in volume. Either the screws have to give, or the plastic. Unfortunately, the plastic seems to have cracked. Tamiya occasionally gets some parts wrong. Most of 3 dozen kits I have are cheap bashers. But a few holes were too tight on DN-01. Fiber-reinforced plastic is tough. The screw would get too hot to touch, just from the friction of going in (I should have drilled the holes wider). If it was the same kind of plastic as MF-01X, they would have cracked. While some plastic could be forgiving, I prefer to stick with the screws the engineers intended.

While I do not have TR-15t, I have 2 other Tamiya nitro trucks (Mad Bison and Terra Crusher). They are fine. I'd look up "needle adjustment." That's where most people have a hard time. If the fuel is too rich or too lean, any nitro engine would have a hard time starting. It's not really a rocket science. You just give less fuel or more fuel and it will start. 1) When you start it for the first time, you would want to keep it idling for a tank or two. Also keep it rich (so the engine would get lubricant--even though it'd be smoky). After that, less fuel (lean) tends to be easier to start. But lean fuel runs hot, so you'd want a temp gun. 2) I'd get an after-run oil, and develop a habit of using it after every single run. It lubricates and neutralizes alcohol in the fuel. Alcohol trapped in the engine attracts moisture. Alcohol evaporates eventually. But water trapped in the engine does bad things to it. 3) Glow plugs are disposable items. So you might want a few at hand. 4) Most nitro trucks can't back out. Making a bit of a room to turn around would be a good habit. (Terra Crusher is rare in that it could reverse, I wish Tamiya kept the reversible nitro trucks.) 5) It would be best if you keep the fuel bottle closed. As mentioned, alcohol attracts water, and water in fuel isn't good. (If you keep the bottle open for an hour on a rainy day, it might go "bad." On the other hand, if you use it on dry days and keep the bottle closed as soon as you fueled the truck, it should last months.)

I did not know that! (I knew that you are the resident Tamiya Nitro guru, but how did you even find out subcontractors for Tamiya?!) I wish Force sold directly, but if I knew the part numbers, it would help the search greatly. Thank you for the information!

We all expect everything would improve or at least stay the same. But we all experience ups and downs life throws at us. I hope you come out the other end better than before what got you down.