JEGS G-Body Double-Hump Trans Crossmember 700R4/4L60E

This is the JEGS double-hump transmission crossmember, part number 640601, for 1978-1988 GM G-body cars. It supports the tail of a 700R4, 4L60, or 4L60E under the factory frame, which is exactly what you need when you swap out the original TH350 or 200-4R for an overdrive automatic and the old crossmember no longer lines up with the transmission mount. Fitment covers the SB-Chevy G-bodies: Chevrolet Malibu and Monte Carlo, Buick Regal and Grand National, Oldsmobile Cutlass, and Pontiac Grand Prix.

The double-hump bend is the whole point. Those two raised humps clear a true dual exhaust so you can run pipes on both sides of the crossmember instead of pinching them or notching the member to make room. The bar is formed from steel and finished in black powder coat, so it holds up to road spray and does not turn into a rust streak under the car a season after you button it up.

Installation is straightforward on a factory-style G-body frame: it bolts to the frame rails and picks up a standard rubber transmission mount (mount and hardware are not included, so grab those separately). A couple of fitment notes worth knowing before you order. It is built for frames that have the driver-side extension running back to roughly the transmission mount, so it will not fit Oldsmobile Cutlass Supreme models or the Chevy El Camino. Some 1983 Hurst Oldsmobiles came with a 2004R and already have the needed frame extension. On engine and transmission swaps, expect to do some trial fitting and minor adjustment to get driveline angle and mount height where you want them.