LS SwapTransmission Cros smember 78-81 GM A-Body

The LS Swap Transmission Crossmember 78-81 GM A-Body by TRANS-DAPT (Part No. 6422) is a bolt-on steel support structure engineered to mount modern LS-series transmissions into classic General Motors A-Body and G-Body platforms spanning 1978–1988. This crossmember is the critical structural component that positions and secures fourth-generation LS transmissions—including the 4L60E, 4L65E, 4L70E, 4L80E, T-56, and TH400—while maintaining factory-correct geometry and load distribution beneath the vehicle frame.

Constructed from structural steel with black paint finish, this crossmember weighs 23.29 lbs and measures 12.4 x 7.6 x 22.2 inches, proportioned to fit within the original A-Body/G-Body tunnel without modification to the floor or frame rails. The bolt-on design eliminates welding requirements, allowing installation without permanent alteration to the chassis. TRANS-DAPT's precision manufacturing ensures proper transmission alignment and support for vehicles carrying the increased torque loads typical of modern LS power plants swapped into vintage Chevrolet and Pontiac platforms.

This crossmember serves restomod and street-rod builders executing LS engine and transmission conversions in first and second-generation A-Body models—including Chevelle, Malibu, GTO, Lemans, and similar platforms—where modern engine technology is combined with classic body lines. Installation requires coordination with exhaust, cooling, and driveline routing; the crossmember establishes the reference points necessary for accurate transmission mounting and ensures driveshaft angles remain within acceptable operating range. Whether supporting a naturally aspirated 5.3L, a turbocharged LSA, or a 6.2L LS9, proper transmission mounting via this crossmember is essential to durability and reliable power transfer.