the only thing I've run across with anything on the GMC specifically is Daves site here that says "around 1000 for the 4 years", making them much rarer than the Chev, which is what I'd expect

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