If you are using the 1/8th diffs and you want to use the revo driveshafts, you don't need a drivecup, as used on most diffs, but you need a pin with a hole.
Luckely, the holes as positioned in the trx5454 stub axles can be used in the diffs to accept the plastic driveshafts. you only need to cut off the threaded part. Get it?