I use the Lunsford 2 1/4 " turnbuckles on the front and rear camber links, and 2 3/8" ones for the steering with the stock black AE ball cups. The rods "bury" into the stock cups with no threads showing and therefore they are stronger, and they NEVER pop off either.

Losi ball cups belong on Losi cars...RPM ball cups should remain on the peg board at the hobby shops.