The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Stock 1970 Eaton clutch style Posi unit- Will it hold up?

Markuli · 06-12-2019, 10:01 AM

Hey all,

I picked up a factory Eaton 4 series posi from a guy off Facebook marketplace for 100 bucks. He says it's out of a 1970 K10. Supposedly it was rebuilt in the 90's or some time around then so I'm thinking maybe the clutch packs have been replaced. The guy seemed pretty genuine, he had a bunch of chevy projects and a sweet bracket race Vega... He replaced these diffs with E- lockers when he rebuilt the K10's axles.

So since I'm not changing gear ratios, my plan is to install my original 3.73 ring gear on the unit, shim it up properly, seal it back up and be on my merry way. I may have to change the diff bearings too, methinks.

Now, I do have a ~500hp 406 in my truck, but I'm also running cheap 275's that don't hook. Down the line I'm planning on running a TKO600, at which point I'll do the right thing and buy a fresh Eaton posi, all new bearings, and seals. But for now, do you guys think my cheap Facebook find will let me put two strips down on the pavement without an issue? I know that anything can happen and it's really a crapshoot when it boils down to it, but what's the harm in hearing some testimonies of those with similar experiences, right?

06-12-2019, 10:01 AM	#1
Markuli Registered User Join Date: Apr 2018 Location: Riverdale, NJ Posts: 85	Stock 1970 Eaton clutch style Posi unit- Will it hold up? Hey all, I picked up a factory Eaton 4 series posi from a guy off Facebook marketplace for 100 bucks. He says it's out of a 1970 K10. Supposedly it was rebuilt in the 90's or some time around then so I'm thinking maybe the clutch packs have been replaced. The guy seemed pretty genuine, he had a bunch of chevy projects and a sweet bracket race Vega... He replaced these diffs with E- lockers when he rebuilt the K10's axles. So since I'm not changing gear ratios, my plan is to install my original 3.73 ring gear on the unit, shim it up properly, seal it back up and be on my merry way. I may have to change the diff bearings too, methinks. Now, I do have a ~500hp 406 in my truck, but I'm also running cheap 275's that don't hook. Down the line I'm planning on running a TKO600, at which point I'll do the right thing and buy a fresh Eaton posi, all new bearings, and seals. But for now, do you guys think my cheap Facebook find will let me put two strips down on the pavement without an issue? I know that anything can happen and it's really a crapshoot when it boils down to it, but what's the harm in hearing some testimonies of those with similar experiences, right?