Jim, if you're replacing the diff pinion seal, be aware that the correct size is 1.625 (41.275mm)shaft, 2.75 (69.85mm) housing, and .5 (12.5mm) thickness. These are no longer available I think, so the next best standard size is 1.625shaft, 2.75housing and .375thickness. Shaft and housing are exact, the difference in thickness doesn't matter, and in fact gives you more choice of fitting position to avoid the wear groove.
I mention this because I have had the wrong sized ones sold as replacements from two different suppliers before, and in the end got one to size from a bearing supplier. I mentioned it to Martin and he was going to look into it.
Nut needs to be TIGHT, and I've Loctited mine for good measure!
Thanks Colin, I have one from Martin and will check those sizes tonight. As you said the thickness shouldn’t matter hopefully. Was planning on marking the nut position and numbers of turns off so could torque it correctly. Will the seal width affect that? Will use the lock right plan too thanks.
Heard to also use gasket seal around the outside of the pinion oil seal also to help stop leaks
Best of luck trying to torque it up under the van. The problem here (apart from being under the van) is that the half shafts have a lot of flex. See the last post in my Jennings Restoration thread for a method of getting the nut off and tightening it back up without winding the van along the garage (or worse, off the ramps!). The seal makes no difference to this. Shouldn't need any sealing round the outside, apart from lubrication, as it is rubber and should seal OK as long as it's the correct size.