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2WD or 4WD Frame?

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prairie

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Have a supposed '79 K30 Regular Cab Camper Special that we are starting to work on. It came with Custom Deluxe badges on the fenders,and has 400SB/TH400/NP203/D60/FF14.
When looking over the shackle flip I noticed that the holes on the side of the frame are spaced 5 1/2", but 6" on the shackle flip. The bottom two holes are 2 5/8" apart on the frame, but 3" on the shackle flip. According to the manufacturer, the hole spacings are correct on the shackle flip for a K30.
Plan to weld the holes closed on one end of the frame, bolt up the flip to the three remaining holes and drill 3 new holes.
I was told by a couple of aftermarket offroad parts builders that some of the late 70's K30 crewcabs and duallies were built on 2WD frames.
Is this a 2WD frame?
Any other way to tell if this is a 2WD frame?
Could this be factory original, or as I suspect, some parts swapping by a previous owner?
 
Frames do have numbers stamped on them,usually on the passenger side rail near the tranny crossmember...

I dont know if you could decipher the numbers using a GM parts listing to find out what it was intended for..

I'm sure someone here knows some other identification methods,a 2wd frame should have holes for the front crossmember cradle,and some other differences...
 
Frame rails should have the part number stamped on them, I believe the 69-72 truck site has the parts manual that would cover that year, should be pretty easy to figure out.
 
Stamped numbers on outside of frame near transfer case crossmember
6 240 right side
375246

6 244 left side
375245 (also an 8 or B in a circle stamped between the 6 and 244)

large print painted yellow on top of the frame near the same location is
FX 7790-20

VIN from cab is CKR347J..., which matches up with the registration, and what i was told the pickup was supposed too be.

No luck trying to research these frame numbers yet.
 
dyeager535 said:
375246 and 245 will be the part numbers. Usual practice if two parts are pretty much identical but opposite sides.

Parts catalog links don't work for me, hopefully they do for you: http://67-72chevytrucks.com/vboard/showthread.php?t=545416
Click to expand...

I downloaded the manual from there this morning, after my first post, but am now just having time to look it over.

Also took measurements for width, height, and thickness at several points on both my 86 K30, and 84 M1008 CUCV frames, and they match the 77 frame, so it is at least a 30 series frame. Still suspect it is a 2WD though.
 
Parts and illustration manuals take some time to figure out, once you do they aren't that bad.

I forgot though, try the illustration manual first. Depends on how they break the variants down, sometimes you'll get lucky and find the part number there, instead of just the group number.

Did you get the part numbers off your other frames? In google skimming somewhere I saw a "superceeded by" comment, but not sure if that related to the frame part numbers. Don't know enough about those vehicles to know whether the frame rails changed over the course of a few years, or just everything riveted to it.
 
I don't know much about anything but 4WD, but wouldn't a 2WD have holes on the front of the frame for the control arms?
 
Have to go back and look at the threads on 2Wd to 4WD conversions folks had done, but you'd *think* GM would have had one frame rail made per side, with all holes punched for both 2 and 4WD apps. Since everything suspension related was riveted or bolted to the frame anyway, it would have saved money, and that's usually what drives them to do anything. :)
 
rampage said:
I don't know much about anything but 4WD, but wouldn't a 2WD have holes on the front of the frame for the control arms?
Click to expand...

Don't know where I would find one to look at for comparison. Where are these holes located exactly? Pictures?
 
Ummm Ive never had a 2wd square body but isnt the front of the frame completely different? Like as in the 2wd frame has giant pockets in it for coil springs?
 
That chart shows a different location for the cab body mounts. I find that hard to believe, even if it's a small difference (5/16"). Looks like a difference at the very rear (frame rails) too which also seems unlikely as that would require two different trailer hitches, and different bumper brackets, since bumpers shared the same bolt pattern.

Edit: I'd like to see pics of the 2WD frames. For some reason I thought all that front stuff was bolted on?
 
dyeager535 said:
This is supposedly a pic of a 2WD frame, can clearly see it's got the holes for the rear spring hanger already there.
Click to expand...

I know that GM liked to reuse parts from year to year and model to model to save money, but if that pic is really a 2WD frame and has the rear front spring hanger hole already, then shouldn't my 4WD already have the holes for the 2WD hardware?
 
IF I'm right, which I can't guarantee. :) You'd think there would be a bunch of extra holes, yes. I don't think many of us have experience with 2WD's, thus the guessing so far.

The rails very well may have been different 2 vs 4WD, there may be reasons it was necessary, but the cab width difference leads me to question those drawings at least. May be different, can't believe there is a different width between the cab mounts.
 
What about the upper control arm brackets? The uppers had dog bones that bolted to an angled piece that I coulda sworn was also welded on.
 
Everything factory will be riveted on. 2wd vs 4wd rear spring hangers are different, 2wd shorter than 4wd. If this was converted over 2wd to 4wd, the front would be higher than the rear, in less a block was in there. GM don't think used blocks after the 60s maybe the early 70s. There will be holes in the frame for the control arms, can't remember how many. But not on a 4wd frame.
 
b454rat said:
Everything factory will be riveted on. 2wd vs 4wd rear spring hangers are different, 2wd shorter than 4wd. If this was converted over 2wd to 4wd, the front would be higher than the rear, in less a block was in there. GM don't think used blocks after the 60s maybe the early 70s. There will be holes in the frame for the control arms, can't remember how many. But not on a 4wd frame.
Click to expand...

But doesnt a 2wd frame still have spring pockets for a coil?
 
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