Right, but part of the reason the one way in in the there to begin with, is so your nitro engine can "coast". Ever see how your truck rolls back after you let off the gas? That's the clutch and the one way working together to allow your drivetrain to spin freely in reverse.

It might work, but I think you're going to have problems. I know it will be more like a 1/8 scale center diff setup but since it's an actual transmission, you might see more carnage.

Yeah, the only reason to lock the tranny is to allow the motor to be used for reverse and/or braking. Since nitros don't have full power at lower rpms, first gear is there to give you low-end grunt, yet allow fast speeds when shifted in second. If you lock the tranny, you'd almost have to have a substantially larger motor to have the torque AND high speed. If you're concerned about less rotating mass; don't be. The extra gear (first) that is removed is very light and has neglible effect.

The one way bearing in the tranny is so that first gear can disengage when 2nd kicks in. The Traxxas SportMaxx was single speed and it did just fine as a basher, albeit with a 30mph top speed. I agree with Brian, no reason to do it with nitro, I was just noting that it can/has been done and works just fine, minus the drawbacks we already discussed.

Im thinking about locking my truck into 2nd, becuase I hate the feel of my truck when it slams into second. throws the truck sideways, or causes a wheelie(I cant imagine what that does to my diffs), but I want to keep mechanical brakes. Can you do that?

Sure can. Just disable reverse and brake on the ESC.

how do i make those 3 indents on the silver circle?

I started it with a dremel and cutting stone, then finished it with a small round file. Takes no time at all.

when making those half circles on 3 corners, does it have to be exactly the same place? or could i do the half circles on some other side?

Well, the half-circles have to line up with the holes in second gear...

I'm still a bit confused as to which pins I need for the pin mod. I'm pretty sure I need #5145. Is there anything else?

The output shaft can be easily drilled out to use the Revo outdrive pins. However, since the input and intermediate shafts seem to be hardened, drilling them is a chore. Besides, those shafts are already kinda small in diameter and drilling them larger may weaken them. So, I've had good luck with using the pins found in the FOC kit (they seem to be harder) and cutting the smooth pin down a little and using two for each spot, one on each side of the gear hub. This post (earlier in this thread) shows you what I mean.

So only one of the pins need this mod? Where do I get more of those FOC pins? Thanks!

You'll need 2 pins for each shaft you need to mod.

Need to know how many shafts need the mod. I can do the math from there.

I believe BrianG said the input and output shafts should modded.

His quote
Those pins replace the ones currently in the tranny. There are two places where these go; on the input gears (blue ones in the pic in the first post), and on the output gear that is on the output shaft. These pins secure the gear to the shaft.