No, you can just drop the driveline and back off the flange nut, remove the drive flange and the seal is right there. If you loosen the nut by hand you can somewhat gauge how tight it is then run it back down to where it is. You can even go as far as marking the nut to the tip of the pinion gear to make sure it goes back to where it started....IF you have a crush sleeve. Nothing to worry about if you have a solid spacer...but yet again neither will be known unless you remove the front bearing which is directly behind the seal.
Just to add, on the outside shell of the seal, when you install it to the housing, use a bit of blue loctite to seal it to the housing. just be sure not to get any loctite on the seal lip. Then be sure to lightly scuff the sealing area of the drive flange hub where it contacts the seal so it will "seat" to the new seal. Lightly grease the seal too so it won't be dry to the drive flange hub. Also, on the pinion nut washer, use loctite on both sides of the washer and some on the threads of the pinion shaft before you install the nut. This will prevent fluid leaking from the splines of the pinion through the drive flange.
Install your driveline and you should be finished.
