crankshaft main caps on farmall super m

Anyway, if your motor is still on the tractor with crank in place, and inserts still in the caps, then you know where the thrust cap goes (thrust bearing is the 'C' shaped one with sides), you will have to measure clearances (plastigauge, etc) to determine proper place for the other two.

If motor is totally dissasembled, again, start by identifying the thrust cap which should be the center cap on this motor (center cap on H/M series, rear cap on A/B/C series). (there should be two caps with similar casting marks and one that's different, that is the thrust cap.) You also need to know what direction they face. You often get lucky if the bolt holes are slightly offset drilled on the thrust, the sides will not line up when on the wrong way. Once you find that one you can usually go by casting numbers facing the same way to get the others that might not be so obvious. You will need to measure the diameter in each bore and do a select fit to find proper place for the front and back caps. Good luck,
Stan(VA).

If you follow Farmer Bob's suggestions, and get the caps in the correct postions, look VERY CLOSLY with them cleaned up well... The rods were honed at the factory with the caps on, and the mains were align-honed with the caps in place, so in all the cap bores, if you look closely enough, there will be hone marks that will match up if everything is in place as it was when it left the factory.