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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Rear Drivelines, Drive Axles and Gearing => Topic started by: mark.comeaux.18 on February 21, 2015, 03:05:27 pm

Title: rearend gear ratio on standard 73 c10
Post by: mark.comeaux.18 on February 21, 2015, 03:05:27 pm

I want to know what gear ratio came original in my 73 c10 swb 307 2brl. thanks

Title: Re: rearend gear ratio on standard 73 c10
Post by: zieg85 on February 21, 2015, 03:18:59 pm

Find your RPO sticker and see.  It could have come with several different ones

Title: Re: rearend gear ratio on standard 73 c10
Post by: Irish_Alley on February 21, 2015, 03:20:16 pm

you might be able to find the rpo codes in the glove box. other than that the only way to have an ideal is to inspect your rear differential

Title: Re: rearend gear ratio on standard 73 c10
Post by: Captkaos on March 17, 2015, 11:54:55 pm

Assuming it hasn't been swapped out in the past 42 years...

Title: Re: rearend gear ratio on standard 73 c10
Post by: sbx22 on March 22, 2015, 10:34:01 pm

I remember reading that trucks originally equipped with v8's had 3.40 gearing, v6 3.73.

Title: Re: rearend gear ratio on standard 73 c10
Post by: Blazin on March 24, 2015, 05:30:17 am

Could have been 3.08, 3.73, probably not likely but could have been 4.10. I would bet on 3.08, or 3.73, but it could have been  change in the last 40ish years.
V6 wasn't even offered until 83 if I remember correctly.
3.42s were not offered until 81/ 82ish either.

Title: Re: rearend gear ratio on standard 73 c10
Post by: Captkaos on March 24, 2015, 12:21:45 pm

The standard axle for 12bolts was 3.08, the standard for 10bolts were 2.76.  So if it doesn't specify on the RPO sheet it is one of these. 80%+ of these trucks came with this..