2WD,5 speed,trans input shaft bearing R&R

I don't have it apart,do I have to disassemble the trans?Or just the front?I'm not a trans mechanic.I'm auto tech (25 year journeyman)

If you can pull the bearing off the shaft, with a puller of course, and install the new bearing WITHOUT pulling the shaft foward, then that is all you need to do to replace the input shaft bearing.....Now if the shaft slips foward enough, needle bearing will fall out!! THEN you have to disassemble the unit!! If that happens, buy a manual or www.alldatadiy.com