I think i found a COPO engine Weird suffix

[Woj]

Back in the early 70's, my brother spun the bearings on the 396 in his 69 SS Chevelle. He went to an engine exchange in Cleveland and bought a 427 out of a wrecked 68 Chevrolet Cleveland Police car. I just checked with him and it had an IS code on it. I've also seen multiple times where Tonawanda used a number in place of a letter, so I'm betting your I5 is an IS engine. By the way, it was a two bolt main car that he couldn't destroy. He and the next three owners tried, but that engine never failed.

Phil W.