I have an 85 k20 with a 6 inch skyjacker lift, front springs and rear add a leaf and blocks. In 4 wheel, and only under some load the front driveshaft c.v. joint at the t-case hits the crossmember. I have added spacers to the crossmember to lessen driveshaft angle, but no dice. I have heard that on some models there is a torsion bar that connects the t-case to the bell housing to reduce movement but my truck doesnot have this part. i have read that you can notch the crossmember but i dont want to cause a weak point by doing so. The truck performs very well even with the banging but i am sure it will lead to some kind of hell down the road. I have searched endlessly and cannot find an answer that makes sense. Any info is much appreciated!!!