I modified the TH350 crossmember. The best thing to do is once you have the transmission bolted to the engine, lift it up from the rear high enough to slide the crossmember in there, bolt it to the frame then drop the transmission to see where the transmission mount sits. Then go from there. I hope this helps. I had to cut about 2 inches off the crossmember tab where the mount bolts to and then drilled new holes to match the new transmission mount position. Let me know how it turns out.