GM-GMC: 1980 350 transmission rear seal leak, auto parts store, rear seal

Question
QUESTION: Where the driveshaft connects to the transmission there is a major leak if I remove just the driveshaft will I be able to remove the seal and replace it or do I have to also take out the transmission?

ANSWER: well in my experience as long as it's not the main seal you can PROBABLY do it without removing the trans but because i can't see the vehicle i could not be for sure and would not want to advise to much ... i would call like an auto parts store and ask if anyone is familiar with this.

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QUESTION: Ok Thanks I did get it out without removing the transmision replaced and even after keeping the transmission full with fluid it is still not wanting to shift out of 2nd gear its almost hard to find the gears on the stearing column when trying to shift do you have any advice?

Answer
well it seems to me that the gears are slipping and stuck so that means more then likely the damage was already done and you stoppin the leak is too late. at some point this tranny was too low on fluid which caused the gears to rub metal on metal and probably ground it down far enough that it doesnt shift because it doesnt catch... when this happened to me on my cadillac it would stick in first then shift out after grinding a bit. i tried changing the fluid to make sure it was clean and replaced the filter but i eventually had to have the trans rebuilt