Identifying frame year
 

Hey all,

I’m trying to figure out what year my frame is. This is all I could find, it’s stamped upside down on the passenger side frame rail. I rotated the picture for viewing. There’s no marking near the steering pump as i thought there was for the 2nd gen. So I think maybe a 73-87 frame?

Any idea?

Thanks

Re: Identifying frame year
 

Is there a partial vin starting with a C or a T on top of the frame rail?

All 73 and up will have leaf springs.

73 and later frames will have the brackets or marks were the brackets were for the gas tank (s) too.

Remember that 1/2 ton GMC 67/72 were usually leaf spring if you are going by rear springs.

Re: Identifying frame year
 

It’s got coils. Added a few quick pics as well.

Re: Identifying frame year
 

What year is your truck?

Your frame looks exactly like my '70 frame.

Re: Identifying frame year
 

It’s a 72.

Re: Identifying frame year
 

3987562 was replaced by a subsequent part # December 1971. Your frame would then be early model 72 I'm guessing. 4 22- Date code?

It's that or I'm reading it backwards, I don't recall that stamp on my 71. Either way it's period correct.

Your VIN is probably stamped as mentioned. Mine is in two places. I can't check, but one near the transmission cross member. I think the other is forward the firewall. Both are on top of the LH frame rail.

Re: Identifying frame year
 

Driver side top of the frame rail should have a partial vin number stamped right under the cab as well as the top of the frame by the steering box if it’s a 72 frame. Earlier trucks especially GMC are known to not have vins by the steering box. Not sure if the earlier trucks had the stamp under the cab or not. My 72 K20 did. You will have to lift the cab to see the vin under it. But the other by the steering box is pretty easily seen if the frame is clean.

Re: Identifying frame year
 

Thanks for the info. So those locations are not excess-able unless the cab is off?

Re: Identifying frame year
 

I do not have the marking near the steering box which is why I didn’t think it was a 72.. maybe gmc then?

Re: Identifying frame year
 

Any chance the paint is pretty thick and covering it over? The stamping on mine is legible but not that deep. Initially I had to wire wheel the frame to find it.

Re: Identifying frame year
 

Possibly but I do not see any evidence of anything. The other picture I posted is very defined with the same paint on the frame..

Not willing to scratch the nice paint to look for it at this point haha

Re: Identifying frame year
 

I totally understand. I was prepping mine for Fresh paint. Could certainly be you’ve got an older frame or maybe even for one reason or another yours is original and just didn’t get a vin stamp. Hard to tell for sure after all these years.

Re: Identifying frame year
 

You'd need a mirror to see the one behind the transmission cross member. I can't check the one in front, because the frame is wrapped up. The front stamp may be underneath the cab, but I thought it was forward the firewall. I don't see it on my other truck (72 C-20).

Re: Identifying frame year
 

It’s definitely under the drivers floor board on my K20. Really really hard to see with the cab on. I checked my pictures of my build but I didn’t take any pictures of that vin.

Re: Identifying frame year
 

I ran my hand across the top of the frame on the drivers side and did not feel any indentation for anything stamped.

I did just notice this on the drivers side frame under the cab but on the side of the frame.

Rebuilding my carb today so will take a look around some more.