I went with Bilstein 5100's on my Suburban with 4" lift. I believe I got them from allshocks.com , if you search for Bilstein on google it should come up.
The price for the Bilstein's is a little high, but totally worth it. The ride is so much better, on and off the road.
I don't have the part number handy, but if you check that website, the listing is easy to find.
Good luck!
Clay