BDS 6" lift

[76stepsidechevy]

Im in the process of putting in a 6" bds lift on my 76 k10 shortbed (350 465 205) and im looking for some advice. Ive lifted jeeps in the past but this it my first truck. I put in the rear springs this weekend with a newly built 12 bolt rear (got rear ended, broke the rear and one stock spring) The truck had an old 4" rancho kit with front springs and rear blocks before.

The new 6" bds rear springs have a degree shim on them and I have some vibration starting at around 50 mph. Im wondering if I need to drop the t case or should try running without the shims or different shims. I have a two month old tom woods driveshaft that was in the accident but seems undamaged.

The new front springs which I ran out of time to install this weekend also have shims. Im afraid using those shims will correct my pinion angle but take out some caster and make it wander on the road, Its got quite a rake to it now with those old sagged rancho springs up front and its hard to keep straight already. Im also wondering if i'll need to make any other changes up front as far as steering.