Oil Leak

Hello,

I have a 89 Chevy 4X4 1500, with just over 200K miles on it. It has been leaking oil over the past few days, seems to just be leaking when I am driving it to work. It seems to be using about a quart of oil every 40 miles or so. Looked under the truck last night and the bottom of the truck is all covered in oil. Someone stated that it was the rear seal that had went out of the motor. I was just wondering how hard that is to change on a 4 wheel drive? On top of that its a standard, just heard that its harder to do repair work on a standard than an auto.

Thanks
Ken