Welcome to the bolt. This is a great place for information.
If the truck has a 4 speed transmission in it, It will most likely be a SM420. This transmission was used from late 1947 through 1967. It is a great transmission. It is very popular with ones building rock crawlers. The PTO was an add on unit, and should have a cover on the side of the transmission where it bolts on.
Have fun.
Jim
