Couple of six cylinder questions
 

First question ... I'm wondering if there is a way to tell the probable rear gear ratio from decoding the drive train options on the vin.

1972 C10 6cyl Th350 positraction rear axel

Second question ... I've never had one of our trucks (this is a burb) that has or had a six. Is there a difference in cross members for six and 8, or does the six just mount in different holes. (btw, not going back to a six).

Re: Couple of six cylinder questions
 

Not from the VIN. Rear gear information is not coded in the VIN.

But - you've given us enough detail to look at the power train chart in the generic info packet and the answer is...3.73.

3.73 was standard with 3.07 or 4.11 optional.

https://www.gmheritagecenter.com/doc...t-Suburban.pdf

K

Re: Couple of six cylinder questions
 

Yeah I didn't bother including the vin because I knew we just needed some of the info the vin gave us. So its more than likely a 3.73 rear gear, with the only real way of telling is to look at a tag on the rear if its still there, or pop the cover on the rear.

But since the 3.07 and 4.11 are optional would they have been listed on the vin? I'm not a vin expert but I was thinking when you went beyond what was standard all options were then listed on the vin?

EDIT: Forgot to thank you for the Heritage Center link for Burbs ... Thanks!
I've already printed it out.

Re: Couple of six cylinder questions
 

Not from the VIN. Rear gear information is not coded in the VIN.

The VIN will tell you some model and series info, and probably an engine type (for most years) and that's about it.

http://67-72chevytrucks.com/vboard/s...d.php?t=570059

Re: Couple of six cylinder questions
 

I think you mean the SPID, not the VIN. I would think any optional rear axle would be listed on the SPID.

There may be a code stamped on the passenger side axle tube. (see pictures) use the first two or three letters of the code (depending on how many there are) and look it up in the charts here.....

https://www.67-72chevytrucks.com/vbo...d.php?t=578793

The code in the pictures below would be TDE


As far as the cross member question are you talking transmission cross member or front engine mount cross member? The front cross members are the same but the 250 I-6 and V8 engine frame brackets are different. Also the 250 I-6 mounts in the rear holes on the top of the frame rail and the V8 mounts in the front holes. The 292 I-6 is a completely different animal as far as mounts......

LockDoc

Re: Couple of six cylinder questions
 

Depends if it's a 2 wheel drive [C-] truck or a 4 wheel drive [K-] truck. In K- trucks, with a 292 L6, a special 292-only diagonal crossmember was used. But a 250 didn't need a special crossmember.

Re: Couple of six cylinder questions
 

Oops, yes I dunno why I was kept saying vin. I meant use the vin to get the basics, and if there are options would they be listed on the SPID ... Im sure trying to help me sometimes makes a person shake their head ... Haha!

It is a C10 and I was talking both cross members. Looks like you guys have me all straight except for the part where I was typing vin and meaning spid =)

Re: Couple of six cylinder questions
 

Ah - so by "VIN" you meant "SPID". I'm married - I know how this works!

Yes - optional ratios would be listed on the SPID, showing the specific RPO code (ie, GU6; GT4) and actual ratio (ie, 3.42; 3.73) in the noun name.

The base ratio can also be listed on the SPID, but would show the RPO for base ratio (GQ1) and would not list the actual ratio in the noun name. You have to refer to the powertrain charts to determine the base ratio.

K

Re: Couple of six cylinder questions
 

Sidebar:

Holy Jeez! I just noticed the optional ratio for a C20 with the M20 trans was 4.57:1.

Can you imagine putting that bad boy in first gear? You could let it creep along and crawl beside it.

K