Steering Box

[silverado3500]

Are the steering boxes the same on a 4x4 and a 2wd or are they different. (99-04) Mine needs replaced, and a local boneyard has an 04 that just came in with less than 30k on it, but its a 2wd. If I remember I think they are the same, but I need to know before I go and buy it.

Thanks in advance!