I finally found my casting number for my block. Problem is now I'm even more confused. The number is 12550313, which is supposed to be either a gen V crate motor or a gen vi bare block. Since I have the fuel pump boss and the 6 bolt cast timing cover, I'm assuming I'm the bare block. Shouldn't I have a roller cam, then? I have a flat tappet cam....Everyplace I'm reading the gen VI blocks all had roller cams. Is there some bleed-over between the generations? Or is it possible to put a flat tappet cam in a gen vi block? At some point, I should be able to replace it with the roller version since I would have the right casting, correct? Do I have a L19 or an L29, or would I need to include the heads to determine that? I'm also assuming because it came as a bare block there could have been any number of heads put on it, so I'm going to need a casting number from them to determine that. If it helps any, this was supposed to have been a workhorse chassis vehicle, most likely an ambulance, in it's former life. Did workhorse buy blocks and then build them? It would seem they would buy at least a long block, if not a complete engine, but I have no idea.
