Are there different clam shell mounts? I am trying to put my small block into my 78 Malibu and its not lining up. I bought aftermarket frame mounts and a set of clam shells off of ebay. I mean I am not close, its off by over an inch. I cant get the bolt holes from the frame to the clam shells to line up. Any help is appreciated. Thanks Don

probably

Don't know, but try turning them around. You'll notice that the bolt holes are farther apart on one side of the mount.

You cant turn around the clam shells they only have 3 holes that match the holes on the block. Thanks anyways

They engine clamshell mounts are interchangeable side to side as they are symmetrical. Sometimes you have to spread them apart a little to get them to fit over the frame mounts.

Sometimes you just have to fight with them a little. The rubber part likes to slide down a little, which makes it too narrow.

There are different part #'s. For the most part - they're interchangable... except (I think) when you go from a truck to a car.
On my 1980Z I have 1 "correct" clam shell, and I accidentally used a clamshell from a 1989 IROC. It was a PITA installing due to the urethane inserts, but it's installed. I compared the mounts side/side and they appear identical. I didn't compare them against the mounts out of my 1990 suburban, but those look similar too... I'd assume those won't work properly though.

They fit over the rubber fine, but the bottom out before the holes line up. I mean they are at least 1 1/4" from lining up. I will try to get a pic and post.

Well I finally got them to work. I had to use a pry bar to align it. I wonder now if my frame is bent? Anyone else have this problem?

Having to use a pry bar is normal. They fit tight and are compressed tighter when the engine is bolted in. Then the next time you go to put the motor back in the clamshells are really tight.