Re: What differential rear end do I have???
 

You have a 3.07 open diff. Non-posi.

43/14 = 3.07

I zoomed in on the numbers.

Re: What differential rear end do I have???
 

Sweet thanks! I wasn't sure where to lookup the numbers. Any idea what the rest of it means?

So 3.07 is gonna be best possible mileage correct? I have a stock 350/350 with edelbrock intake/carb, headers, HD radiator.

My plans for this truck is get it driving/stopping 100%. It will be a weekend driver, trips to the dump, home depot etc. With the occasional (maybe 3-4 times a year) trailer pull of another 67-72 GM truck on uhaul trailer. I'm gonna add a curt class 4 hitch and a brake controller.

Re: What differential rear end do I have???
 

Ugh!! Leaking!! I knew that diff cover was gonna be a problem.

Should I just order a new chrome one or try to fix this one?? Or load up on the RTV?? I know I'm gonna have to pop the cover off again, drain the oil (do I try to recapture it or buy 2 more quarts?), get a new gasket etc etc.

Re: What differential rear end do I have???
 

If you get a new chrome one, be sure to lightly scuff the mounting surface to give it some grip. The longer number preceding the other two numbers is the part number (begins with 3). A weekend driver with light hauling and trips to the dump is fine. I have 3.07 in my 68 and that is exactly what I use it for.

Re: What differential rear end do I have???
 

I have this coming tomorrow:

https://www.oreillyauto.com/detail/b...r/9894/4514825

Do I use the gasket that comes with it, get a fel-pro, or get green RTV?? With the metal brake line in the way, I could see how a line of RTV would be a pain trying to get the cover on under the brake line.

As far as scuffing the mounting surface, will a red scotchbrite pad work or should it be more like 80grit?

Torque is 20lbs, got that.

I'm gonna be an additional $49 for the cover kit, an additional $16 for 2 more quarts of gear oil and possibly another gasket and more permatex (I used ultra black I had lightly on the felpro).

I just don't want to do this again. :/

Re: What differential rear end do I have???
 

I would use the gasket that comes with it (get a Felpro if it gives you peace of mind), and coat all surfaces with the stuff I posted in post #14. It's the best I have found to seal against gear oil leakage.

Re: What differential rear end do I have???
 

:o Sorry! I wasn't even drinking! Glad you got it straightened out.

Re: What differential rear end do I have???
 

pulled my blazer out ....gear oil all over the floor....looks like I think gasket blew or i hit rear end when car was lowered.

one time when it was at a shop getting air ride installed...67-72 member said rear end didn't look original, might have been swapped out at 1 time....how can I confirm what rear end I have? is there markings on the outside to tell?