You have a LOT of drop. Follow the path. Battery........connections........cables.........starter relay stud........fuse link............bulkhead connector..........ignition switch connector.........through the switch.........out on various switch outputs.........through the switch connector..........back through the bulkhead connector.
Each point separated by dots is a source of drop. There can be one, 2, or all, each one adding a tenth here, a few tenths there. It adds up
The battery cranking, 10.55.......is that right at the battery posts? If so the battery is marginal or low on charge. Either that or the starter is dragging or engine bearings/ something else dragging, or its "really cold" LOL
