I recently replaced this unit and installed new output and input seals. I did not replace output seal to the front wheels since one was not available at the time. It is not leaking.

The problem is that when the truck is driven it blows a LOT of fluid out of the rear seal. A perfect spray pattern on the bottom of the cab. Could the vent be plugged? I pulled the hose off of the vent and ran a piece of wire in and out of the elbow the best that I could. The hose to the vent elbow had been cut off and all that was on there was a short piece of hose. Could this be the problem? Now that I think about it, slipstream air could have been blowing into the case.

The rear output shaft seal was the one that did not have a dust boot cover on it like our 727s have. Napa listed both types but only had the non dust boot one in stock.

Thanks