This part is fully interchangeable with part number 12644HKR. Integral component of the complete Hooker BlackHeart swap system for this application. Component features unique geometry that is not compatible for use with any other brand of engine mounting components. 4L60/4L65/4L70 transmissions require add on bracket P/N 12655HKR. 4L80 transmission require add-on bracket P/N 12656HKR For applications that were NOT originally equipped with a 200-4R transmission, crossmember adapter P/N 12647HKR is required. Crossmember fitment has not been validated for El Camino applications. *NOT COMPATIBLE WITH TREMEC TR6060 TRANSMISSIONS. TH350 Transmissions can reuse the factory transmission crossmember, but the slots in the center of the crossmember will need to be elongated in the forward direction.