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Old 10-10-2010, 12:37 PM   #19
DANTIP
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Join Date: Sep 2001
Location: Fort Wayne, Indiana, USA
Posts: 1,667
Re: Stock rear gear ratio info

Quote:
Originally Posted by capev86 View Post
1/2 ton

12 bolt: 3.07, 3.73, 4.11, 4.56

3/4 ton

corp/eaton 10 bolt: 4.10, 4.57, 5:13, 6:13

Dana 60: 3.54

the 3.54 was standard for the big block 400 as it didn't need as much gearing. the 3.07 was pretty standard on the 1/2 ton with an auto unless you ordered otherwise. my 72 burb c20 automatically came with a 4.57 because it is 2wd and has a manual 3 on the tree. the 4x4 burb got the 4.10 normally as did most c/k 3/4 ton pickups as they are lighter. i put a 4.10 third member in my burb because it was an easy swap and the 4.57 is a little too low once you get rolling. with a q-jet in place of the 2bbl the 307 is much spunkier now because of the quick response small primaries and the extra air flow potential. i picked up a 66-69 saginaw-borg warner overdrive trans (my rig is a 3 on the tree) and that will give me a far better highway ratio than a straight 3.07.....so i get the best of both worlds.
FYI, at least in 72, the only gear available for 1/2 Ton Big Blocks was 3.07.
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