Other posters are correct on mounting. But I have installed M nose ends on 400 gas starters so they could be switched the other way. Only problem is some will have holes to clock at the wanted angle and some needs modification for holes and the line up pin. M starter housing may not have mounting holes for the 400 starter switch. 6 volt gas starter from a 300 to the 350 and 400, 450. is the same. 350 and 450 after change to gas 12 volt starters will work if tractor is using 12 volts now. 400 starter pictured with M nose.