OK, I know that you have the small and large idler shaft cases. Seems like the split is 4/86 to the larger idler shaft. Question #1: Even though the idler shafts are different will the HI/LOW gear assy interchange? The case itself is different but the innards should(?) be the same outside of the idler gears and shaft. #2. The H55F requires the 4/84 or newer case to work correctly without the addition of the original 5spd TC bolts or an aftm repalcement. I assue this to be correct? #3. The difference between the early, pre 4/85, and post 4/85 cases are the length of the spacer plate on the tranny which requires the longer bolts. So, all things being equal, any 60 case will work if you can provide the longer bolts for the early model case and re tube the drive shafts to make up for the difference in lenght. The newer case will require no drive shaft mods and should bolt right up (with the required interior mods) and is stronger as well due to the larger idler shaft. I think this is correct. Opinions?