Gm transmission noise

I have a 95 Chevy G20 van with a noisy bearing that I believe is in the rear of the transmission. With the drive shaft removed I am able to move the splined shaft side to side maybe as much as a quarter of an inch. I doubt that this is normal, if so I would like to now. My question, is it possible to replace the bearing by only removing the rear seal housing without removing and disassembling the transmission? Any other advise or suggestions would be appreciated. Thanks in advance, Vince