I have the rancho5000 on my 85. It rides like there is no suspension at all. I am really hoping that I don't end up with severe back problems because of them.
I would strongly suggest not going with the rancho5000s. Bilsteins work amazingly well though. I really wish I would have gone with those. fyi, my truck had the stock shocks on it when I replaced them last year. Only one of them was severely blown. Also, like Glen said, the Gabrials work well also.