I just bought a '79 K-20 in decent shape. NEW 350, TH-400, 203, 10-bolt, FF14-bolt, 4:10s.
First, the steering seems to be loose, and the truck wanders at freeway speeds. I've checked the steering box/frame connection and it's fine w/no cracking. Ideas?
Also, the truck has manual hubs. I assume these are not stock, as the 203 is a full-time case. Correct?

Is there anything else I need to know about this truck right away? It's got some rust, but it's not bad at all.

TIA!
:)

For the steering issue, could be a few things. Ball joints, tie rod and/or drag link ends. Replace the ball joints and all the tie rod and drag link ends and I bet it drives about 500% better. And it's always a good idea to get the weld in and bolt in steering braces. If it's cracked or not. It will stiffen that area of the frame and help to make the steering more responsive. Also, is it lifted? If so, does it have the raised steering arm? Sometimes people will cut corners with thia truck and not install one. It's pretty much required with lifts more than 2.5". Running without one on a lifted truck will make the steering funky as well.

You are correct, manual hubs are not stock on a truck with an OEM 203.

And last but not least, you should check out the forums at www.coloradok5.com Best place on the web for fullsize GM truck tech of this vintage.