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| | | Forums66 Topics128,068 Posts1,055,883 Members48,428 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
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For helping keep this great
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on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Jan 2008 Posts: 28 Apprentice | | Apprentice Joined: Jan 2008 Posts: 28 | looking for a posi unit for a 70' c-30 eith 18"dual wheels.want to keep the 6.17s but want posi.any help? | | | | | Joined: Oct 2003 Posts: 5,152 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Oct 2003 Posts: 5,152 | We need to know what rear you have under the truck. There is not a 6.17 available for the factory Eaton rear. The original rear would have 4.10, 4.57 or 5.14 gears.
There is a locker unit available for the Eaton rear. It was factory installed in some trucks and probably shows up here in the swap meet or on eBay.
I've seen them for sale but don't know of any right now.
1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble... | | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | Actually, there is a 6.17 ratio listed for the '67-'72 C30. The axle code is MX for '67-'69, TMX for '70, TAS for '71, and RAS for '72. I won't necessarily say that it is the HO72 axle, though. I'm more inclined to beleive that it's actually the 1.5 ton axle from the trucks that used the standard pickup front end sheetmetal and IFS. I have seen a few of those trucks, but they were all badged as C40s, rather than C30. They were also GMCs, not Chevies.
Bill Burmeister
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