The difference on the Gen 5 motors is the block and head have different logo's and markings on them. The block has more flywheel clearance, the carb is all black on the hsn side, some early gen 5's came with long lsn, the newest ones are short. The biggest difference is the crank, the crank weight is more like a v-spec and is a little heavier on the gen 5. Running the old vs. new the new gen 5 is smoother and makes it better in a buggy.

Rex