Review on Efficient Axle Shaft Seal Installer for Ford 1998-2004 F-250/350/450/550 – OTC 6695 by Joshua Douglas

Not the cheapest tool you will ever buy but was very solidly built. You really have to tap that seal to get it in. I used an 8 pound hammer to hammer the seal onto the shaft and used a plumber to set the seal into the housing. This sets the seal to the exact depth so there is no guessing how far it needs to be seated on the shaft. Again, it's not cheap, but cheaper than $100 an hour for a mechanic (who may or may not have a similar tool) and about the price of a seal if you mess it up by putting it in without tools.