Rear end question

[Sparkplug79]

What gear ratio would be in a 79 chevy custom deluxe? it has a 250 6 banger, turbo 350 trans and a 12bolt rearend.

I tried searching but i couldnt find anything about it.

[silvereagle07]

You can take the cover off, count the teeth on the ring gear and divide it by the number of teeth on the pinion. Ring gear/pinion= gear ratio. You can also raise the truck, put in neutral, mark pinion flange, mark tire, rotate tire and count number of revolutions of pinion flange. That will get you close.

[Dooley]

Originally Posted by Sparkplug79

What gear ratio would be in a 79 chevy custom deluxe? it has a 250 6 banger, turbo 350 trans and a 12bolt rearend.

I tried searching but i couldnt find anything about it.

The 79 C10's without options and 6cyl were usually listed as having as 3.07 rear. That said, there was also available,
2.56
2.76
3.40
3.73
The "Big 10" came with the 3.40 except CA where the 3.07 was standard.

[billnorman]

THANK YOU DOOLEY!!! I put a Big 10 rear end in my '85 C10. I counted the gears twice and came out to 10/34 twice (3:40). Everybody says there is only 3:43's. but NOW i'm absolved. Yes, Virginia there is a 3:40!!!!

[Dooley]

Originally Posted by billnorman

THANK YOU DOOLEY!!! I put a Big 10 rear end in my '85 C10. I counted the gears twice and came out to 10/34 twice (3:40). Everybody says there is only 3:43's. but NOW i'm absolved. Yes, Virginia there is a 3:40!!!!

The 3.40 axle ratio listed for some GM vehicles 1976-81 and carried a HE4 code.

[Sparkplug79]

Hmm that's interesting. Was a 12 bolt standard for 79?
The only options my truck has are power steering, power brakes and that's it haha