i bought a 9 inch rear,with 31 spline Moser eng.
axles, it had 2 1/2 by aprox 10 inch brakes,
i have to get a "pumpkin" locally
one local,small wrecking yard wants $150 for a "posi", setup,if he has one,for 31 spline
{i hope i get lucky}

Anyways, there is no vent on the axle,as far as i can tell, on the front side there is 2 round
things,but on the inside i feel no openings,where they are.
Do i need to drill/tap a hole for a vent; and if so where?

Also aprox how much gear oil will i need,and 1 or 2 bottles of additive? Is the "generic" additive ok to use?

Eaton has this to say,for their stuff.
Recommended Lubricants*
1) Texaco 9622; Mineral Based 80W90
Available from GM Service Department, Part No. 1052271
2) Limited-slip differential additive
Available from GM Service Department, Part No. 1052358
3) SAE 80W90 (API-GL5 Level performance or better)
* Limited slip additive (top-treat) should be utilized with all lubricants [4 ounce bottle].

Following these tips will help you get the most out of your new Eaton® Posi. If you need more information, please use the e-mail function of this page to e-mail your question to us. Drive carefully and thank you for spec'ing the Eaton Posi.
Please, any ideas?

Thanks, Lee, cavemanmoron smile.gif

Most of the 9" Fords vent through the bolt that holds the brake line distribution block to the housing. The bolt is hollow. I weld this hole shut and drill a new hole close to the end of the housing. I drill a 7/16 hole and use a plastic push in vent from a GM rear end or transmission. It should hold about 2 to 3 quarts of oil. I use Amsoil 75W90 Series 2000, but if you want a petrolium oil you should use 80W90 and a bottle of the Ford additive #M-19546.

I weld this hole shut and drill a new hole close to the end of the housing. would this be near the axle /brake end, or near where the tube is welded all the way around the larger part of the center of the housing?

thanks for letting me pick your brain,again Big!

I am trying to learn,i sure don't know everything yet! ;)

I drill the new hole near the end where the housing end is welded on. Don't go out to the weld, stay about a inch from it so you don't get into the axle seal. I try to get the vent on the outter side of all of the suspension parts so that torque from the differential will not twist the axle tube where the hole is. I have seen axle tubes torn through the vent hole on drag race cars. I also don't know everything yet, and probably never will. graemlins/thumbsup.gif