Suspension lift for K30

[ChevyKev]

I'm also not too keen on rear blocks.

Neithewr am I - the shackle flip is the way to go. Either ORD or your own - and there are a few ways to do that.

So I guess I'm asking if 5.5" or 6" lift with the Dana 60 requires extensive driveline work or expensive steering correction.

Anytime you put 5-6" lift on something it will need driveshaft work. There just normally isn't 10" of travel in a drive shaft (6 that you dropped, and 4 to engage splines = 10.)

Also, would the Tuff Country springs be heavy enought for the diesel?

See what Mark said about spring rates and such. Though I doubt those spring rates would equal a 5/4 ton spring rate, it would probably do ok.

I was worried about the dual cardan driveshaft over 35 MPH. I tow my Bobcat in the winter and use 4WD on the roads.

Do you not already have a dual cardigan in there? Most stock Chevies do. 2 u-joint in the rear, 1 in the front. I have 6" lift on my blazer and that driveshaft, without clearancing, and a Dana 60 front does fine. Granted, I had to get the proper length shaft after the lift, but since then it's been fine.