[Blown353]

If RS does the full tunnel replacement to all their builds with their frame, it’s probably needed.

Be sure to leave extra clearance to take into account for the floor flexing downwards a bit if you ever put 4 people in the car.

When I reworked my tunnel I removed the bump stops from the rear axle, pushed the axle all the way up until the axle tubes hit the frame to simulate a worst case scenario, then set 1” high spacer blocks on top of the driveshaft and set the new tunnel sheet metal on top of those spacers to make sure there would be at least 1” of clearance to the driveshaft, and then tack welded it in.

Makes for lots of driveshaft room (and the tall vertical walls of the new tunnel section actually help to stiffen the floor in bending from front to back) but it does make the carpeting job a bit more difficult as you can no longer use a standard Chevelle carpet kit. I used a standard Chevelle carpet kit for the sides but had to have a local upholstery shop do the tunnel carpet, they cut matching material and sewed welting on the ends where the tunnel portion met the floor portion.

Also had to rework the rear seat lower frame and springs in the center to accommodate the raised tunnel. It still looks stock over the tunnel, but I wouldn't want to sit there anymore... LOL