What to look for in a 4x4

[Elpresidente]

I'm going to check out a '73 K20 shortbox this weekend. I've never owned a 4x4 in this bodystyle, are there any key spots/things I should check for to make sure i'm not buying a piece of junk? I mean things related to what kind of diffs the truck will have, any problem areas to check for frame cracks, any useful information to save me a headache down the road. It's a farm truck, so I can expect that its been used and abused, but I might get lucky.

[Sartobuilt]

Check the frame really good. Look for loose rivits especially around the front end. Check for cracks on the engine crossmember and by the steering box. Rot in the rear spring front hangers.

Farm trucks get beat.

[DustyRusty]

K-20s (3/4 T) did not come w/ a short box.  Only K-10s had short boxes.  How many wheel studs, 6 or 8? That is more critical to make the correct diagnosis.  Both K-10s and K20s had the Dana 44 front.  Half tons will have either 10-bolt or 12-bolt rear diff depending on GVW.  Three fourths tons should have full float 14-bolt rear. IIRC, all 73s had the NP205 tcase.  IMO you won't have many problems w/ any combination of axles on this truck.

[Elpresidente]

Ok, thanks. I havent seen the truck yet, he says its a 3/4 ton but I didnt think they made a 3/4 ton shortbox either so it must be a K10.

Also, can frame cracks be welded and still keep the truck safe and solid? I was thinking of just building it into a bush truck anyways.

[Jason S]

Dusty is mostly correct.

There were no regular production K-20 (3/4 ton 4x4) or even C-20 (3/4 ton 4x2) trucks made.  It may be a shortbed K-10 with 3/4 ton axles under it.  1973's could be had with a NP203 transfer case. 1973 K-10 and K-20 trucks had Dana 44 front axles.  I'm also fairly certain that if it was a factory '73 K-10 it would have been a 12 bolt rear end.

 Of course parts could've been swapped around in the last 39 years...

[bake74]

     Since it is 4wd, while doing the test drive, make sure to put it into 4wd and drive forward and backwards, straight and turning in both directions.  Drive slow and then faster while in 4wd, this will tell you if there is any problems with the drive train that could get expensive down the road.
    And like you said, it is a farm truck, so expect it to be used a little.

[Elpresidente]

Checked it out; it was pretty rough. there was a 1" rust hole right through one of the leaf spring mounts, frame was questionable, and the truck was sunk almost up to the axles in the ground from sitting. The killer for me was when i grabbed the box sides and was able to shake them back and forth about 6", Ill keep looking haha.

[bake74]

Checked it out; it was pretty rough. there was a 1" rust hole right through one of the leaf spring mounts, frame was questionable, and the truck was sunk almost up to the axles in the ground from sitting. The killer for me was when i grabbed the box sides and was able to shake them back and forth about 6", Ill keep looking haha.

     That is a good idea unless you needed a parts truck.