[mr48chev]

I'm pretty sure he is saying that because of the side mount bracket bolt hole that you can see in the bosses just behind the generator on the side of the block but they are 58 and up for passengers cars and the same block is probably used on trucks from 58 through 61. There is also always the possibility that someone swapped 235's in the 58 sometime in it's past but matching the engine number stamped in the pad on the passenger side of the block with the vin number should clear that up.

You might be able to fab up a pair of brackets that bolt to the block on the three bolt holes and have the motor mounts bolt to them so that they will fit up with the aftermarket crossmember. That should work fine but might look a bit clunky and you may want to take that crossmember out and build some brackets that run over closer to the frame and use a different and cleaner biscuit or cushion. A couple of the guys have setups like that on their 250's and 392's in the early trucks that would give you an idea or two.