Been helping my son with his 96 f250 351w. His clutch clutch went out. So I gave him one from my old 408w that I had in a 85 f250 4x4. His has a zf 5 sp and mine had a 4 sp with a granny 1st. Now his clutch won't disengage. I've found that the 2 clutch sets have different part #s. Could this be the problem ? I'm in Florida and he's in Indiana so I haven't been able to compare the two. Any help appreciated.