Well te rear bearing on the old tail housing as I’d mentioned earlier is the tapered bearing. The 2003/2006 tail has the one piece counter balance shaft and that rear bearing is a slightly different bore with a retaining ring to hold the bearing in. So I’m unable to use the tail housing from my 2000. Solution is to use the Gen 3 tail housing and drill out the hole for my speed pick up. After man months and digging into this. The Gen1 looks and mounts up but can’t handle the gen 2 torque and HP, gen 1 ,2,3 can bolt into a gen 2 but no speed pick up in the Gen3 tail housing.
Basically they can all bolt up but each one was designed for the increased HP and torque to the perspective years.
Should have the gen 3 single counter balance shaft rebuilt and tail housing modified for the speed pick up.