[George16]

It's okay. You're still going to use the UE Ultralites. I bought those before too but ended up going the 1/8 scale diffs. With what you bought, you still have to drill and enlarge the stock ring gear to 3mm. It's not included in the package. I know exactly what's in the package because I bought 3 sets of those before.

Drilling and countersinking the traxxas ring gear will be a pain in the ass especially if you don't have a drill press and carbide-tipped bit. It was easy for me to drill the ring gear because I have a drill press and carbide-tipped bits.

If you go with the UE for TRX gears, all the required shims and bearings are included. It may or may not include the aluminum cups (depends on availability). If you go with the FLM route, you need some 14x16mm, 10x12, and 6x8mm shims in varying thickness.