Will the 496 cast iron ex manifoulds fit any other mec engine .

Thanks for any help .

they will fit most big blocks just need new bolts the 496 has metric bolts

A yes.

Metric between the risers and manifolds.

no into heads also sometimes get in the way of power steering hose and no mounts on manifolds for shift and computer

Depends on the version. The version with the separate cast water rail will interfere with the location of the alternator. I purchased a relocation bracket from IMCO to solve this, but in the end went with Stainless Marine. I also moved my shift control and oil filter to the transom, and mounted my ignition module to the cylinder head.

You will need to run a 3/8 drill bit through a couple of the mounting bolt holes... some are tight.

Lastly, you're going to run into some alignment issues with the exhaust tips at the transom, though the hoses will make up some of the difference. Issues vary from installation to installation. I ended up going with Stainless Marine because of this (I needed longer risers with my set up... I guess I could have turned the risers some, but the SM parts worked much better).