I think you should find the correct shocks listed at a good parts house, whether they're still available or not ... the front and back are different because of different loading front and back ... not sure GMC is the same, but the Chevy numbers are:
rear, Monroe "Limited Edition" LE10018 [pair] or Gabriel 82060 [each] ... front, Monroe 3100 or Gabriel 82047

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot