Your 91-92 should be an MUA5. Borg Warner also had a transmission offered in some of the early 90's trucks but I believe it's case was removable and it wasn't as common. Ya I'm not sure what's up with the aftermarket flywheels just saw the part numbers were the same awhile back. Either way it's not a catastrophic issue. I'm still debati8ng if I wanna go 5-spd swap with an MUA5 or just swap the TOD case for an earlier manual case. If I keep it auto the wife can drive it if need be, if I swap it, well then I need to teach her how to drive a 5spd lol. At least the MUA5 would be basically bulletproof behind our motors.