I have no argument with your research as it is correct. I have wheels here from an M15 and an R15 and it could be that someone put an R15 differential under the M15. However the wheels have the beveled holes which lead me to believe they will fit with stud centered rim. They will fit the R15 axle which as you say are hub centered. The M15 they came from was not a complete truck so who knows what the history is.
Posted on Jun 9, 2017, 11:32 PM from IP address 22.214.171.124