I never had a hard time rebuilding shocks or diffs. I always use naptha to clean the old silicone oil from the shocks or diffs, wash it denatures alcohol and air dry them using my compressor.
Castle Neu 1520 on 6S LiPo Powered Gmaxx (Nitro Killer)
Predator with OS .21TM
Supermaxx with Mach .26
Revo with OS .18TZ
Kyosho ST-RR Conversion
Ofna CR with Tekin ESC/Motor (2)