(SOLVED -ish?) HELP! Lug nut thread pattern shenanigans

[someotherguy]

2GCGK39N3K1245200

Without an actual lookup via Compnine etc. a simple VIN decode reveals:
1st digit 2 made in Canada
2nd-3rd digits GC Chevrolet Truck division
4th digit G is the GVWR, range of 8,001-9,000 lb
5th digit K is 4WD
6th digit 3 is series, 1 ton
7th digit 9 is extended cab
8th digit N is 7.4 engine
9th digit is an internal check digit
10th digit K is 1989 year model
11th digit 1 is Oshawa Ontario plant
12th-17th actual serial #

Duallies are typically 4th digit H for 9,001-10,000 lb GVWR. With that I am 99% sure your truck is a conversion from a SRW 3500. I have records of several old parts trucks of mine that were 3500 SRW and also 2500's with 4th digit G, and duallies with 4th digit H.

Arrowcraft is a company that offered kits with spacers, wheels, etc. ...they used to offer them for GMT400's complete with the fenders. Could be one of those kits, or could be just spacers and someone sourced an OEM dually bed.

Richard

 

[618 Syndicate]

Unfortunately, FWIU they only have records for post 1990 trucks. But it's worth a try...

Good to know, but unfortunate in this case if so.

 

[618 Syndicate]

Just went outside and looked at the two one-ton trucks in the driveway. My 98 dually has an H as the 4th digit, brother in law's 91 srw has a G.

 

[someotherguy]

Just went outside and looked at the two one-ton trucks in the driveway. My 98 dually has an H as the 4th digit, brother in law's 91 srw has a G.

Having them on-hand to look at quickly sure is helpful. The "G" fits for 2500's and 3500 SRW's both since the 8 lug 2500's are generally 8600 lb GVWR. The 3500 SRW's I have build sheets on are 9010 lbs which doesn't *exactly* correlate to the VIN decoding info; technically that extra 10 lbs of capacity should give it an H. but for example, that particular 3500 SRW I am mentioning is indeed a 1GTGC... VIN, meaning it's a US build, GMC division incomplete chassis (chassis cab), 1 ton, 8,001-9,000 lb GVWR - yet the build report as looked up by a GM dealer shows its GVWR to be 9,010 lb... I guess a few pounds and they don't want to fudge the classification.

I've kept pictures of old inventory, SPID labels associated when present/legible, and build reports as I was able to obtain them. It's often a handy research tool.

Richard

 

[1ton-o-fun]

Wish I had good news...

 

[618 Syndicate]

Having them on-hand to look at quickly sure is helpful. The "G" fits for 2500's and 3500 SRW's both since the 8 lug 2500's are generally 8600 lb GVWR. The 3500 SRW's I have build sheets on are 9010 lbs which doesn't *exactly* correlate to the VIN decoding info; technically that extra 10 lbs of capacity should give it an H. but for example, that particular 3500 SRW I am mentioning is indeed a 1GTGC... VIN, meaning it's a US build, GMC division incomplete chassis (chassis cab), 1 ton, 8,001-9,000 lb GVWR - yet the build report as looked up by a GM dealer shows its GVWR to be 9,010 lb... I guess a few pounds and they don't want to fudge the classification.

I've kept pictures of old inventory, SPID labels associated when present/legible, and build reports as I was able to obtain them. It's often a handy research tool.

Richard

The 91 srw 3500 I looked at is actually a square, so that might make a difference.

 

[SasquatchOnDeck]

Without an actual lookup via Compnine etc. a simple VIN decode reveals:
1st digit 2 made in Canada
2nd-3rd digits GC Chevrolet Truck division
4th digit G is the GVWR, range of 8,001-9,000 lb
5th digit K is 4WD
6th digit 3 is series, 1 ton
7th digit 9 is extended cab
8th digit N is 7.4 engine
9th digit is an internal check digit
10th digit K is 1989 year model
11th digit 1 is Oshawa Ontario plant
12th-17th actual serial #

Duallies are typically 4th digit H for 9,001-10,000 lb GVWR. With that I am 99% sure your truck is a conversion from a SRW 3500. I have records of several old parts trucks of mine that were 3500 SRW and also 2500's with 4th digit G, and duallies with 4th digit H.

Arrowcraft is a company that offered kits with spacers, wheels, etc. ...they used to offer them for GMT400's complete with the fenders. Could be one of those kits, or could be just spacers and someone sourced an OEM dually bed.

Richard

Well, bit of a mystery solved i guess. Anybody have enough experience with the rear fenders to identify OEM vs this conversion? Honestly this might be good news, Knock on wood if it was converted FROM SRW, the trip back shouldn't be too rough. And the bed replacement, even if it is just the wide hips added, would explain the respray making it look original. I'll snap some pics of the fender and check for logos, markings, and paint colors.
And thanks for that info dump, my 88 was an Oshawa truck as well.

 

[618 Syndicate]

Feel or look inside the fenders and check out the wheel opening in the bed. On a factory dually it's unfinished. If you can get pictures of it I will tell you what you have. I swapped out my fenders a month or so ago. I've got the old ones in the burn pile still if we need to compare specific stuff.

 

[454cid]

Well, bit of a mystery solved i guess. Anybody have enough experience with the rear fenders to identify OEM vs this conversion? Honestly this might be good news, Knock on wood if it was converted FROM SRW, the trip back shouldn't be too rough. And the bed replacement, even if it is just the wide hips added, would explain the respray making it look original. I'll snap some pics of the fender and check for logos, markings, and paint colors.
And thanks for that info dump, my 88 was an Oshawa truck as well.

I think your front flairs are aftermarket, unless it's just an early or dressier style that I'm not used to. I think the shape is different plus they have the chrome at the very edge.

The whole truck could be a conversion, just a bit more low key than most. It would have been done right when it was new, as opposed to a guy buying a truck and putting some kind of kit on it. That would explain the seat and why the PO said it was original except for the transmission and shocks. There used to be a lot of conversion companies around that modified new vehicles. I'm sure you've heard the term "Conversion Van".... companies did truck too.

GM shut Oshawa truck assembly down in 2009, but they're in the process of re-opening it, although I think it's at a lower wage.

 

[618 Syndicate]

The rear flares look different to me, the angle of the part around the opening doesn't look the same.
This is a factory flare.