89 mustang lx wont go into 1st

[MANNY87]

i have a aod transmission in my 89 mustang i had it rebuit with a shift kit but before that i couldnt get it to into 1st it will go into every other gear if i adjust the cabe to go into first then it wont go into park. on the original shifter i grinded out the stopper to be able to drop it into first. but now i order a b& m shifter and am back to square one. im thinking maybe the trans shifter lever isnt for a mustang but off another vehicle any ideas?? thanks