I put an original ford OEM seal in......PROBLEM SOLVED!!! I don't want to sound as if I'm bashing a company..but the Yukon Gear&Axel pinion seals are not very good..
I have removed driveshaft 2 times..removed nut and drive shaft knuckle with gear puller..removed plastic dust cover..removed pinion seal TWICE ..replaced both times with a Yukon Gear and Axel 10.5 ford OEM pinion seal..and it's still leaking...it doesn't seem to be leaking around rear end...