Thanks for all the info, They have the same amount of teeth 139 the 235 is from 55 and the 261 is a 55 also. The truck is a 49 3100 still 6V, that had the 235 in it but PO pulled it and was going to put in the 261. so i am thinking that the 55 261 was also 6v if it has the same flywheel. and i can use the plate from the 235 that was in the truck.
