'72 C3500 GMC flatbed project

[JJorgensen52]

Originally Posted by redryder

Thanks guys. The truck will be a driver for the next couple weeks to get some work done around here. I hope to get some more work done soon though.

Rockers and cab corners
Headlight upgrade
Mount and plumb remote reservoir for hydrolics
Rebuild seals on hydrolic pump
Find and mount a plow

On the plow, remember that because of the mix and match suspension hangars you're going to have to do a little "adjusting" - you'll want an '73-'87 mount style, for sure.

[redryder]

I should have ordered the mount so we could get it mounted when your here Saturday. Obviously I have not been planning ahead.

[JJorgensen52]

Doin' work

[flashed]

I am so jealous ,that truck turned out very nice and mine just sits waiting its turn .The bodyshop owner keeps asking when Im going to bring it to him .I have had little time to get it running right and he wants to pull his camper with it soon .

[redryder]

We cut a lot of wood. Rebuilt carb from smi and a hei distributor and the truck is running great!

[rs74]

I am still wanting to get my father n laws 67 GMC C30 and do this. Been looking for a rolling chassis for it if even possible to find. Might have to buy one that runs.

[rs74]

Just a couple of questions. Was it just going to be too much work to adapt the older cab to the newer frame to make it work verse the way you did it? Are the C30 frames similar in height and thickness as the ones from the newer square body? Also how do the 67-72 K20 frames compare to the same year C30 frames as far as frame height and thickness.

I ask because I know with the 73+ 30 series frames that are more stout than the 20 series. Just trying to put some things together in my head in case I get to do this to the 67 GMC C30. I have a line on an 85 K30 rolling chassis. I knew that it had been said that it probably would have been easier to use the 67-72 K20 frame but wondered if they were less stout than the 30 series frames either of the same vintage or the newer square frames.

[7dee2]

If memory serves correctly and I could be wrong their square body frame was pretty bad that the donor parts came from so using the old C30 frame made sense. Just as strong and the body all ready matches the frame. My research is that the Cab & Chassis frames are very similar in many, many ways and not so much in a few others.

I really like this build also and have committed to building a similar truck (see link). We have gathered parts to go either way but using a 84 GMC K3500 Crew Cab frame is making more sense in our situation for now.

[JJorgensen52]

Originally Posted by rs74

Just a couple of questions. Was it just going to be too much work to adapt the older cab to the newer frame to make it work verse the way you did it? Are the C30 frames similar in height and thickness as the ones from the newer square body? Also how do the 67-72 K20 frames compare to the same year C30 frames as far as frame height and thickness.

I ask because I know with the 73+ 30 series frames that are more stout than the 20 series. Just trying to put some things together in my head in case I get to do this to the 67 GMC C30. I have a line on an 85 K30 rolling chassis. I knew that it had been said that it probably would have been easier to use the 67-72 K20 frame but wondered if they were less stout than the 30 series frames either of the same vintage or the newer square frames.

I will answer as best I can, I've been away from the board with the holidays and call.

As far as I was able to tell, the late square body (mine was an '87) had a taller frame section in the center under the cab. I do think the '72 frame was a bit thicker, though. Either way, both trucks had a similar GVWR on the frames.

The major issue with doing a cab swap, to my understanding, is that there is a difference in the location of the core support - the square body frame is longer in front of the cab than the 67-72 frame. I did not compare the cab mount locations, but the square body's rear mount is definitely taller and would have to be modified.

The reference I made to the K20 somewhere earlier in the thread was with regards to hangars. The K20 and K30 trucks share their front springs, mounts and hangars. The sway bars are not the same, but the mounting points are.

So, my original plan was to buy axles and springs from a square body, then find a 67-72 K20 donor frame for all of the front hangars, etc. However, I happened to get a REALLY good deal on a complete truck with a rusty frame, so that made the most sense for my project.

I cannot verify this myself, but I believe the frames in the early square body K30 (1978 - 1980) is different than the 1981+ frame, which is ASYMMETRIC in the front, which created some issues for me with the cross members. Nothing undoable, just food for thought.

[rs74]

Originally Posted by JJorgensen52

I will answer as best I can, I've been away from the board with the holidays and call.

As far as I was able to tell, the late square body (mine was an '87) had a taller frame section in the center under the cab. I do think the '72 frame was a bit thicker, though. Either way, both trucks had a similar GVWR on the frames.

The major issue with doing a cab swap, to my understanding, is that there is a difference in the location of the core support - the square body frame is longer in front of the cab than the 67-72 frame. I did not compare the cab mount locations, but the square body's rear mount is definitely taller and would have to be modified.

The reference I made to the K20 somewhere earlier in the thread was with regards to hangars. The K20 and K30 trucks share their front springs, mounts and hangars. The sway bars are not the same, but the mounting points are.

So, my original plan was to buy axles and springs from a square body, then find a 67-72 K20 donor frame for all of the front hangars, etc. However, I happened to get a REALLY good deal on a complete truck with a rusty frame, so that made the most sense for my project.

I cannot verify this myself, but I believe the frames in the early square body K30 (1978 - 1980) is different than the 1981+ frame, which is ASYMMETRIC in the front, which created some issues for me with the cross members. Nothing undoable, just food for thought.

Thanks. Still kicking around the idea. Sounds like it would be easier to find a K20 chassis and then stick the one ton axles underneath. The only thing I am not sure on these year trucks (67-72) are how much heavier the 30 series is over the 20 series. I have come across an 85 k30 chassis that I could get the axles off of but would have to find a hydroboost set up. It's coming down whether I want to sell my 86 K30 to fund the project.

[JJorgensen52]

Originally Posted by rs74

Thanks. Still kicking around the idea. Sounds like it would be easier to find a K20 chassis and then stick the one ton axles underneath. The only thing I am not sure on these year trucks (67-72) are how much heavier the 30 series is over the 20 series. I have come across an 85 k30 chassis that I could get the axles off of but would have to find a hydroboost set up. It's coming down whether I want to sell my 86 K30 to fund the project.

Just ran across this post in 7dee2's project thread the other day:

http://67-72chevytrucks.com/vboard/s...75&postcount=9

There is a surprising difference in the strength of the frames, even though they are visually very similar. More food for thought. Depends on what you're going to use the truck for. This truck was built to WORK

[1972K20]

I remember seeing this build when the pics would show up. Do you still have the pics saved?

[redryder]

I know he does still have the photos. I think he was looking for a new photo hosting platform to avoid paying photobucket.

On a side note, the truck is just finishing up getting its bed rebuilt and some body work done. She will be back to work soon, I'll post pictures soon.
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[rs74]

I wonder if this ol girl is still going.

[JJorgensen52]

Originally Posted by rs74

I wonder if this ol girl is still going.

Sure is! Still doing farm work. It actually just got a Sniper EFI installed, I helped clean up some wiring yesterday and took my oldest out for a quick test drive 😉

[21ctd]

How do you like the sniper efi?

[7dee2]

Very nice, looks like a fun day!

[geunther]

Hope I can ask a question.

I too have installed the Sniper and think it was worth it. I am still running the stock points distributor which makes getting the fuel map correct a challenge.

It looks like you have the Holley distributor, coil etc. It also looks like your spark plug wires run the factory routing? If so, where did you source those due to the distributor being different than my current wires.

Love your truck btw.

[rs74]

Originally Posted by JJorgensen52

Sure is! Still doing farm work. It actually just got a Sniper EFI installed, I helped clean up some wiring yesterday and took my oldest out for a quick test drive 😉

Awesome! I would love to see some more of these "K30" builds on here.