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Discussion Starter · #1 ·
I am in the process of replacing leaky 30 spline axle seals in this 373, 12 bolt 8.75 inch rear on my 64 C10. The rear came with the truck, the numbers on the axle case are WA 6 09. and the raised stamp on top of the pumpkin is 3838227. All I'm able to determine is that the rear is a 373 from the WA code. Does anyone know if the 6/09 is the production date? If so, this rear is not original.
Most importantly, I noticed what appear to be clutch packs behind both sides of carrier side gears. There are no springs like in a normal posi. Is this some kind of a limited slip? I read that Easton used some kind of LS setup, but couldn't find more info. It's driving me crazy trying to figure out what I have, and if I should tear apart the carrier and replace the clutches..
Any help would be greatly appreciated!
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What’s up Timberfield if you are tearing into your rear end I recommend buying the 1963 c10 and 1964 c10 shop manuals. they are available online as pdfs. (The 1964’s almost entirely us the 1963 shop manuals, with exception of a few 1964 year specific changes such as body). From what I know, those numbers are month and day. The letters WA as you correctly state are in the shop manual as “(3.73 ratio) (Exc. Positraction)” So unless you have the positraction option, or someone at some point took apart the rear diff or axles, you probably have the regular standard Chevrolet single speed rear end.
I have a 1964 C10 Fleetside longbed, those shop manuals are a must have IMO
 

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Cant tell from the pics posted,but if you rotate a half a turn and see a cylindrical object on a pin then its a gov lock posi which was a standard posi used on gm trucks.When one tire starts spinning the governor has weights that open to engage the posi.Otherwise it works as a normal open diff.Now early ,early models had bellville washers in the clutch pack that were cone shaped creating a spring like action to load the clutches.so it could be either style.The later is what I have in my 55.We tightened it up by adding an extra clutch.It was pita to do but it made it a lot tighter
 

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To add to above, if you had positraction option the stamp code would be “WC” so most likely you have the standard Chevrolet one speed rear end. Can I ask if your VIN code is 4C14xx? If so then the WA rear end would most likely be the original. Mine VIN is 4C15xx, stamp WE, mine is the 3.73, non-posi, 3500lb axle capacity. I will try to add a couple photos to show you how to find yours
 

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Cant tell from the pics posted,but if you rotate a half a turn and see a cylindrical object on a pin then its a gov lock posi which was a standard posi used on gm trucks.When one tire starts spinning the governor has weights that open to engage the posi.Otherwise it works as a normal open diff.Now early ,early models had bellville washers in the clutch pack that were cone shaped creating a spring like action to load the clutches.so it could be either style.The later is what I have in my 55.We tightened it up by adding an extra clutch.It was pita to do but it made it a lot tighter
To add to Blue Goose, it IS possible someone at some point made your rear end a POSI. If so I would go with his description to determine. To add to the confusion, if it is a same period Chevy POSI you are right in your first post, there would probably not be springs but only clutch pack & shims you are seeing, unlike springs what you are used to seeing in a POSI
Good Luck let us know what ya find out
 

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Discussion Starter · #6 ·
To add to Blue Goose, it IS possible someone at some point made your rear end a POSI. If so I would go with his description to determine. To add to the confusion, if it is a same period Chevy POSI you are right in your first post, there would probably not be springs but only clutch pack & shims you are seeing, unlike springs what you are used to seeing in a POSI
Good Luck let us know what ya find out
Thank you all for your help! This is definitely a WA rear, and appears to be the original to the truck.There are no bevel washers or gov lock mechanism. So, I'm thinking someone did indeed put a posi unit in at some point. It looks like they must have just tossed the S spring or spring pack for some reason. Either way, both axles are pitted at the seal surface, the ring and pinion are worn out, and all the berrings are shot. I made the decision to buy a new 373 rear from Moser. Nice stuff, Eaton Posi unit, roller berrings and a cool trac bar setup. The cost was a little more than Jasper quoted to rebuild mine, but it's a nicer rear. Next is transplanting my GM crate motor and rebuilt 700R4....Then I'll be good to go!
 
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