I believe the housing on the rear of your four speed that the bell goes into will change out with a housing for a seal and open drive u joint. I may have one laying around. That four speed closed drive u-joint is a sought after item by people wanting a four speed in their half ton. As much as I dislike the closed drive you won't gain a lot changing to an open drive if you are going to keep the original tranny, just a little easier/cheaper to work on.
Grant
