Tranny swap problems, vibrating badly

[eddielugnutz]

I sold my friend a T5 from a 86 Gt, he put it in his 90Lx, and it is vibrating violently and gets worse with acceleration, he said it's so bad it feels like the shifter is going to come loose, he noticed that the input shaft was a bit longer on the 86 than on his 90T5, and that the splines appeared shorter, does anyone know if these trannies are even compatable from year to year, I was told that any T5 could fit any year, the only obvious difference being in the clutch size in 86 when they increased to a 10.5" clutch, so then that leads me to believe that the problem is just mechanical with the transmission, not a compatability issue, my friend is taking the tranny out tomorrow to inspect it.