The entire Holley swap system (brackets, mounts, oil pans, accessory drives, etc.) is designed to decrease your total swap installation effort and cost, while increasing the engineered quality of your vehicle and compatibility of these components with other popular aftermarket components. The experts at Hooker BlackHeart have taken away the guesswork of where to position your engine swap and we've followed up on our popular GM G-Body LS line with a new version that allows you to choose LS or LT engines by utilizing 4th Gen F-Body clamshell engine mounts. To complete the engine mounting be sure to follow these steps: 1). Choose the proper clamshell for your engine: Gen III/IV (LS) - 71221018HKR Gen V (LT) - 71221019HKR 2). Add the thru bolt kit: GM LS/LT/Gen III Hemi - 71223015HKR 3). Choose the polyurethane insert in the color you prefer: Black - 71221016HKR Red - 71221017HKR For the transmission, this kit is designed to be used with the same G-Body transmission crossmember already in production (12644HKR-1) for a trouble-free installation and optimized driveline angles. This system is compatible with almost any popular GM transmission, even modern 6-speed, 8-speed, and 10-speed applications. An adapter kit may be necessary for applications that were NOT equipped with a 200-4R transmission from the factory - Part # 12647HKR. 12644HKR-1 - Transmission Crossmember (no additional adapter needed for TH400/200R4/T-56/Magnum) 12655HKR - 4L60/65/70/75 Transmission Adapter - use with 12644HKR-1 12656HKR - 4L80/85 Transmission Adapter - use with 12644HKR-1 BHS5181 - 10L80/10L90 Car Transmission Adapter - must be used with both BHS5182 and 12644HKR-1 BHS5182 - 6L80/90, 8L45/80/90, 10L80/90 Transmission Adapter - use with 12644HKR-1 BHS5183 - Tremec TKX 5-Speed Transmission Adapter - use with 12644HKR-1 *For installing a 10-speed GM car transmission, both BHS5181 and BHS5182 will be used together to achieve the proper spacing and alignment.