Here's the notes I copied from various posts on the subject.
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Sorry for the delay in getting back to you but I have just started reading the "Panels 'N Burbs" forum again. You have an easy one! Since there are NO 5 lug front drums, you get discs in the process! My preferred way is to pick up a '73 - '88 front cross member complete! It bolts on and later you won't have to go crazy remembering what you did. You have to drill 2 holes that are not in the early frame and use grade 8 bolts.If you don't have it, now is the time to add power steering, too. You will have to "dimple' the frame behind the steering box for the later box. ALSO, whether you go to power brakes or not, you MUST change the master cylinder to one for disc brakes and use the bias valve that comes from the disc brake truck! The bias valve is hiding in the front cross member on the donor. The old "donor" truck is your friend! Another way to do it is outer tie rod ends, lower "A" arms & ball joints, and of course the brakes themselves along with their spindles. Donor truck or expensive kit, whichever! This leaves you with a collection of different year parts in your front end that I don't like. However you go, replace the rubber lines and calipers, as well as any metal brake lines that need it! It is really easier than it sounds!
'71-'98 1/2 ton 2wd uses a 5x5 bolt pattern, 4x4s stayed 6 lug. They went back to the 6 lug pattern on 2wds with the GMT800 body change in '99. The '88 and later wheels will not work on the earlier trucks without a spacer, the F141backspace is different.
Side note, the cutoff for the crossmember swap is '87 for pickups, '91 if you use one from a Suburban or R35 1 ton Chassis-Cab or Crew cab. The '88 chassis (GMT400) uses a welded in crossmember, with the upper control arm mounts welded to the top of the framerail (sides on 4x4) that are not part of the crossmember.G160
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I don't remember who to quote on each, but I didn't write any of it.
http://www.classicperform.com/ They have some good tech notes and I think they sell the tie rod ends etc to match things up. I'm sure others do as well.