What vehicles had a HIPO 318?

Look at the main bolts on the caps that hold the windage tray. If they have 2 hardened washers between the cap and bolt head, they have been added on. If they have no washers, they are factory and the round boss that the little bolts screw into will be taller than the same bolts that came in a 340 or 360. The 340 or 360 windage tray main bolts will not tighten up when using a 273/318 cap unless you use 2 hardened head bolt washers. If they are true 318 windage tray main bolts, you'd better hang onto them because they are like Hen's teeth!