The engine side mounts that slide are fine, but prefer to use the 73 or newer clam shell mounts. As a full length of metal wraps around them thus called "Safety Motor Mounts". The old style flat ones are not captured and can break. I am not running power adders like turbo's or superchargers. I have my share of turbo failures in the 70's & 80's. Spinning with engine off and no oil, pop-off valves sticking cause a run-away condition. This was factory. Also, clam shell mounts have metal bars to rest onto the bracket for extra support and vulcanized into the rubber. The problem is no metal on the brackets to rest on. Thru bolt is only support, with a OE type bracket they rest at bottom front and rear. I don't like the prices but salvage yards have doubled their price sheet. Still $100+ cheaper than Speedway or Dirty Dingo. Nice build! ASE Master since 78.
When I installed the LT1 in my 37 PU, I centered it on the frame and blocked the front of the engine on the crossmember. My mounts were welded to the. frame that I had boxed. I made templates for the driver side, and then checked them on the passenger side. I don't know how, but they were a perfect match. The Trans mount is part of a Center Section that I got From Paul Horton in Canada that stiffens the hole chassis.
