I am finding my REX is getting old with alot of flight time...starting to have to replace bearings. The last set was the bearing block bearings, I didn't have the OE Align bearings handy but I did have a whole ream of new ABEC 3 clutch bell bearings for my Mugen MBX 5 buggy, these bearings are probably used on 90% of the car nitro engine clutch bells. These are slightly thinner that the align stock bearings but they work really well. So if your in a pinch, any local hobby shop should have these clutch bell bearings in stock.