I'm not familiar with this seal but what sometimes happens is the seal wears a groove in the shaft such that the next seal can't do a good job. Short of replacing the shaft, the pinion in this case, polish any grooves and see if you can set the seal at a different depth to run on a clean section of shaft.

Sixto
93 E150 Chateau 5.8 191K miles

 

The 8-14 in.-lbs. is basically the drag. That is how many in.-lbs a dial torque wrench will read while turning the pinion with a torque wrench on the pinion nut. That is not the amount you torque the nut to. If you only torque your pinion nut to 8-14 inch pounds you will have your pinion yoke fall off going down the road!

 

I ran into problems with the front yoke seal (3 times) and rear yoke seal (1 time) on my ram 3500.
The first seal we put I leaked right away.Turns out the old seal, wore just enough of a grovve on the surface of the yoke that it woul dnt allow the new seal to function.

Wh3n they replaced them, they didn't go through the whole by the book process.Basically just a tax tighhter than what it was on with and never a problem.

 

If you still have a leak around the yoke and it turns out to be a groove worn in the yoke shaft, you might research into a spedi-sleeve

Yoke Repair Sleeve for 9" Ford Rear - Speedy Sleeve for rear end yoke
http://www.ebay.com/itm/Yoke-Repair-Sleeve-for-9-Ford-Rear-Speedy-Sleeve-for-rear-end-yoke/151551240572?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D33278%26meid%3D24e4809c3d92432a8629807d126d7e0f%26pid%3D100011%26rk%3D1%26rkt%3D1%26sd%3D150831759525
Make sure it fits your van..


NATIONAL Part # 99181 Redi-Sleeve

More Information for NATIONAL 99138
More Information for NATIONAL 99138

 

here's a example of how the speedi sleeve works

Again check your part number,, i think yours is the 181 number

 

How's the longevity of the seal with the ever so slightly larger shaft diameter?

i have a first aid kit on my bench but it doesn't have Alka Seltzer

Sixto
93 E150 Chateau 5.8 191K miles

 

I prefer a press to a hammer.

 

Pretty much OK right now. The van was parked in the back of the shop at work for quite some time, no drips. Just drove it home the other day, and didn't notice any leaks. I just needed to do it correctly.