We just got done converting a new transmission off a 4908 tmaxx so that it could be used on an aftermarket chassis.
A commom problem when trying to use the newest model tmaxx transmission on either an older model tmaxx or one with an aftermarket chassis is that the chassis cutout for the front center yoke to spin in, is not big enough.
There are two options, use a dremel and bore out channels in your chassis for the yoke to spin in, or convert the transmission back to 4909 specs.
We chose to convert instead of hacking up a nice FLM chassis.
We started with traxxas part number 5195 FOC kit for 3.3 tmaxx.
Inside that kit there is an output shaft and gear that you need. All other components of the kit are not used.
Once you have the transmission out of the truck, first step is to open it up.
Here's what you'll see inside.
Next step is to remove the output shaft as shown here
Step three is to open your 5195 FOC kit and find the output shaft and gear and the screw pin and assemble it as shown. Notice the difference in the one we removed from the transmission (longer one) and the one assembled from the kit (shorter one).
Install the new 4909 spec shaft and gear back into the transmission case the same way the original one came out.
Close up the case and there you have it. All you need now is the center drive shafts and brakes to complete the set up. This transmission will now fit in ALL models of tmaxx trucks including all trucks built with aftermarket chassis.