Chevrolet Repair: 1995 Suburban Rear end leak, shaft seal, base library

Question
I own a 95 suburban w/175K miles.  I have recently noticed under the rear a small oil puddle beneath the rear housing and upon further inspection there is oil thrown up under the floor pans of the truck.  Is this a diff seal leak and how difficult is it to change.  I am mechanically minded as I am a USAF small engine mecanic.  I have never tackled something this big though.  Also what is a good source of repair informaiton/manuals to see what I am dealing with.  Either on-line or througha book.  Thank You

Answer
Hi Mike,
I'd assume it is the input pinion shaft seal.
No great big job to replace. remove the driveshaft, the companion flange retainer nut, the flange, and then the seal.
Tap in a new one, and put it back together.

Go to the public, or base library, and look in the refference section. They have all the manuals you can immagine.

Look in drive axle repair, and you will find step-by-step instructions with pictures.

Van