[TheWhiteElephant]

Okay, I have to clear up some things here.

First off, lowering the T-case is not meant to help with the length of the driveshafts. On '73 and up trucks, installing the lift will increase the angle of BOTH driveshafts. What this does is create a vibration in most situations, especially in shorter wheelbase vehicles like K5 Blazers or short wheel base trucks. Lowering the T-case will decrease the angle again, therefore eliminating vibration in most cases.

Think about it this way--when you lift a truck, you "push" the frame and t-case up while the differentials stay at the same height. The higher the truck goes, the more severe the angle of the driveshafts. Since the driveshafts connect to the t-case, if you lower the t-case, you will decrease the angle of the driveshafts.

I lowered the t-case on a '79 K5 I had with only 4 inches of lift and felt a noticeable (huge) difference in driveline vibrations. Depending on your truck, you may already have some factory spacers on the t-case mounting bolts on top of the frame/crossmember at the t-case bolts. You just need to relocate these spacers to the bottom of the frame between the frame and crossmember. Very easy one-man job.

Bottom line here is that lowering the t-case decreases the driveshaft angles. By the way, I'm not familiar with the '67-'72 suspensions. Hope this helps.