I was wondering the same thing on the weight, my Malibu weights 3253 w/driver, with S/Blk, and the only thing that's fiberglass is the hood and bumpers. It's a backhalf 4 link car, which is heaver than stock suspension. it still has all the dash and gauges, roll up windows all original glass. I am pushing it harder with the 377" but it runs 6.50's with 1.41/1.44 60 ft times.
Zip.