1971 K20- project just get driveable!!

[swamp rat]

My book said 120 on the U bolts also, the other book said 150 but that book also covers 73 and later so i think they goofed and omitted the 70-72 truck.

In my research i figure that there is no need for the shock to extend but maybe about 1" past the fully extended measurement on the truck because the springs cannot physically move any further, so for example if you buy a shock that extends to 26" but your extended dimension on the truck is 21" then your going to find that the body of the shock is so long that you loose a lot of compression travel. the shorter the shock extended length the shorter the body, the more compression travel you will get.

I think 5-6 compression would be great for my truck but i have a 4" lift. I called a couple places today (yesterday) before i went to work, both of them said for my truck and a 4" lift that my 4.25" front and 4.5 rear should be ok.. I'm still a little skeptical but the only real way to know exactly how much compression your system has is to compress the springs till they bottom, but how? even if you picked up one wheel with a forklift the spring is designed to support the vehicle so that won't work.

>>Golden question is just how much further (if any) can the axle go than the axle off ground (dangling) dimension? <<

This is something i didn't consider, i just assumed the spring would hold its shape but I suppose its possible there could be some kind force that might make it flex outward?of change but i cant imagine it being that much. I would guess about 1" would be ok.