insure it?
go through those tests that Eddie outlined, and if it's not them it's an ICM.
assume worst case - is it worth that cost and effort? Can you skip to the endgame and swap ICMs with anyone/anything?
otherwise, apparently there are $800 5.3 Chevy trucks out there that run and drive but break in half. complete swap, and scrap/sell things to have a $350 or less running LM7, 4L60E, 231.