These are just some of the things that I can remember that fit and work.
Traxxas Stampede/Slash/Rustler 2wd and 4wd rear drive shafts.
Traxxas Turnbuckles and camber links from the Stampede/Rustler/Slash 2wd - just buy the ones that are closest in size to the stock ones, they are adjustable.
Team Associated RC10T4 titanium turnbuckles with RPM ball cups and Ecx ball ends.
I've had Traxxas Ultra Shocks on my Ruckus, they might work on the Amp too.
The bellcrank out of the RC10T4 with a little modding. There was a thread on URC about how to do this, I think there might be one here but Idk.
Team Associated RC10T4 caster blocks and front axle carriers. Will need adjustable turnbuckles and camber links.
HPI Firestorm/Blitz caster blocks and front axle carriers. Will need adjustable turnbuckles and camber links.
HPI Firstorm/Blitz Shocks.