This should tell you how it goes together. And you would be able to use a bearing I think. I have had no issues with the bushing though. Mine shows no signs of wear.
http://www.hpieurope.com/manuals/pdf/835.pdf
Savage: FLM Conversion, 6s, MMM, CC 1520.
Mini-T Pro: Micro Pro 6800kv, Lipo, HS-81mg, Dirt Hawgs
M18MT: Quark 33A, Y22S 6000kv, FP 2s Lipo
LRP S8-BX: RC-M Conversion, Tekin RX8 B1600KV, 6S.