C20 sub lowering kit

[Sethmark]

I have a 1981C 20 suburban. I’d like to lower it 3 to 4 inches.

It is unclear to me what the differences between the suburban and the pick up chassis would be that the parts are not interchangeable, however, each time I call a vendor and tell them I have a suburban they freak out and tell me the parts won’t fit.

I assume that there is a spindle and shackles/hanger kit that will lower this vehicle to my liking. Does anyone have any experience with the big suburban?

Thanks so much!