You will need three things; longtail output shafft, longtail extension housing, and front planetary to make sure that the splines of the planetary match the shaft. You can use a small block, AMC, or International Harvester for the parts.
Do you realize that they have 2 planetaries inside?
do you know that the AMC and corn binder parts are all the same as mopar cars? you know the unimportant stuff like the:
speedo gear adapter hole
the output shaft machined gear teeth to drive the speedo gear
rear mount boss
slip yoke size
console bracket boss?