Most do the upper first because its the first piece to bind.If you got the money i would replace them both.
http://michiganmetalworks.com/ has some nice options for the rear if you don't want it to lay frame ride tech has a nice kit.To lay frame bolt on
http://www.newmaticsinc.com/S10_Comp...t_p/123137.htm And thumb around thor bros they have a lot of stuff but are known for taking a long time to ship.For some reason the forum blocked their link so that might be a sign not to use them.