Bolt-in powder coated steel crossmember that puts the mount pad where a 4L80E needs it when you swap one into a 1978-1988 GM G-body car.
This is a bolt-in replacement crossmember for a 1978-1988 GM G-body that is getting a 4L80E. The factory member was built around the short TH350, 200-4R or 700R4 the car left the plant with. The 4L80E case is longer and its mount pad sits further back, so the stock crossmember will not line up with the transmission mount no matter how you shim it. This one moves the mount pad to where the 4L80E actually needs it and drops into the same frame perches.
Fitment is the GM-4 transmission group: 4L80, 4L80E and 4L85E. Vehicle side it covers the 1978-1988 G-body cars: Malibu, Monte Carlo, El Camino, Cutlass, Grand Prix, Regal, Century, LeMans, Caballero and Bonneville. It is fabricated from steel and finished in black powder coat, and the mounting hardware and instructions ship in the box. Overall size is 48.82 x 9.72 x 5.43 inches.
Install order that saves you a second trip under the car: support the transmission on a jack, unbolt the factory crossmember from the frame and the trans mount from the crossmember, then set this one in the perches loose. Bring the transmission up until the mount lands flat on the new pad, run the mount bolts in finger tight, then torque the frame bolts and the mount bolts last. Snugging the frame side first is what leaves you fighting a mount that will not sit square.
Before you button it up, check driveshaft length and pinion angle. The 4L80E output sits in a different place than the transmission you pulled, so the stock shaft is usually the wrong length and the tailshaft yoke ends up at a different height. Measure with the car at ride height on the suspension, not hanging on a lift, or the angle you set will be wrong once the weight is back on the tires.
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