V1500 suspension differences ???

Now I'm no 'burb authority, but not much about your suspension sounds stock. AFAIK the burb didn't have an OEM 4" lift. I don't think a "Z71" package was ever really offered on that body style. AFAIK the rear (stock) shocks wouldn't be coil overs, and either you or the PO put those on to help with some tubby kiddies in the back saggin' dem der springs. Quad shocks simply means 4 shocks, 2 per side, on the front axle. With the advances made in shocks / the fact you probably don't Baja the thing, if you get a quality set you only need 2 per axle.

GMC Gremlin

Must be Quad suspension, Now to figure out if these are long or short shocks on the front. Gabriel shocks lists the V1500 suspension as 1989,1990, 1991. With the Standard, Quad, Or 4" lift as shock options. Dealer must have installed a "Tow Package" on this, That's where the coil over rear shock came from. Previous owner used this to tow his large boat. I have just about rebuilt the entire rear drive line. don