Rear End Gears
 

All, my first time on this site. Looks to be a very informative place. I am just about finished rebuilding the mechanicals on a 68 c10 SWB. Before I can order a new transmission I need to figure out what size gears I have in the rear end. Any idea how to do this?

Re: Rear End Gears
 

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Here is a link to the ratio charts I posted.

http://67-72chevytrucks.com/vboard/s...d.php?t=578793

Posts #8 & #19 show the location where the code numbers should be stamped depending on which rear end assembly you have.

LockDoc

Re: Rear End Gears
 

Outstanding, Thanks! This is exactly what I was looking for. I'll let you know how I make out and post some pics. So far I have installed all new stainless brake and gas lines, tubular front lower and upper arms, new steering linkage and gear box, Airbags, C-notch, new 350HO turn key GM crate engine and new Vintage air system.

Great to have a place to get more info!

Re: Rear End Gears
 

Here are a few pics

Attachment 1486785

Attachment 1486786

Attachment 1486787

Re: Rear End Gears
 

Awesome job so far it looks like a blast

Re: Rear End Gears
 

Pretty!

Re: Rear End Gears
 

LocDoc, Thanks again for the VIN decoders. I looked at my vin and it does not match the decoder for my year.

My VIN is:
CS148S169004
I get the CS1 as being a C-10 6 cylinder but the 48S does not make any sense.

Any thoughts?

Re: Rear End Gears
 

CS148S169004

C Conventional 2WD
S Six Cylinder
1 1/2 Ton
4 Pickup
8 1968
S St Louis
169004 Sequence number

I still thnk this forum needs a "thanks" button! Or a "useful" button. Or a "You decoded it wrong, dummy" button.

Re: Rear End Gears
 

Well done Davepl. Thanks!

Re: Rear End Gears
 

Based on Dave's above decoding of your VIN you originally had a 6 cylinder.
To my understanding all these series of (C10) trucks that came from the factory with a 6 cylinder got a 3.73:1 differential gear as standard equipment.
That said, had it come with a V-8 (option), I believe the default (standard) gear ratio would then have been 3.07:1.
The only caveat to this would be if your SPID called out for something specifically ordered unique or non-standard (ie: 4:11 or a 3.73 in a V-8 truck, etc).
All Good
Coley:chevy:

Re: Rear End Gears
 

Thanks Coley, I was able to get the code of the axel and it confirms it has 373 gears. The next step for me is to find out what size tires I should run to get the best performance and economy with these gears.

Thanks!

Re: Rear End Gears
 

Nice Project Mike. Which transmission are you planning to get?

Re: Rear End Gears
 

The taller the tire, the lower your RPMs at cruise speed. You might want to keep that in mind if you are going with an OD trans.

Re: Rear End Gears
 

I am going with a 700r4 from Phoenix transmission. They custom build one for you based on the rear end gears and the size of your tires. They also have designed it specifically for the ZZ4 GM crate engine.

Re: Rear End Gears
 

Is the rear end a Positrack? "If it aint, it outa be" with that motor and transmission...Looks good! ;)

Re: Rear End Gears
 

Beautiful truck!