The 1978-1988 G-Body Sure-Fit Crossmember is a G body transmission crossmember sold on its own for a G-Body engine and transmission swap. Order it for the transmission you run: 6L80E to 10L90E, 4L80E to 4L85E, 4L60E to 4L75E, T-56 to TR6060, TH400, or Powerglide, TH350 or 4-speed.
Transmission options
- 6L80E to 10L90E
- 4L80E to 4L85E
- 4L60E to 4L75E
- T-56 to TR6060
- TH400
- Powerglide, TH350 or 4-speed
How it mounts on a G-Body frame
The transmission crossmember slides onto crossmember brackets on the sides of the frame, and the transmission mount bolts to it. G-Body frames came with three driver side mounting shelf styles: full shelf, split shelf and short shelf. Full and split shelf frames have two mounting locations. A short shelf frame has only the front location and needs an extra bracket bolted to the frame, which means drilling the mounting holes with a 25/64 inch drill bit.
Tunnel and clearance
Automatics need no transmission tunnel modifications. A T-56 needs a new shifter hole. Due to variations in body, body mounts and frames, you might need to clearance the transmission tunnel or firewall.
Read the 1978-1988 G-Body LS install guide, or see all 1978-1988 G-Body LS parts.
Frequently asked questions
Which transmissions does the G-Body Sure-Fit crossmember fit?
It is offered for 6L80E to 10L90E, 4L80E to 4L85E, 4L60E to 4L75E, T-56 to TR6060, TH400, and Powerglide, TH350 or 4-speed. Choose your transmission when you order.
Will I have to drill my G-Body frame?
Full shelf and split shelf frames have mounting locations for the crossmember bracket. A short shelf frame needs an extra bracket bolted to the frame, and you drill those holes with a 25/64 inch bit.
Does a G-Body need transmission tunnel work?
Automatics need no tunnel modifications. A T-56 needs a new shifter hole. Some cars may need the tunnel or firewall clearanced due to body and frame variations.