If you just take your time, but a little oil on your new seal to lube it up, you can put it on without an alignment tool just fine. That how I installed mine. No problems', no leaks.
'77 CJ-5 Renegade 304 / T-150, Dana 20, 30/20 axles, Aussie Locker in the Dana 30, American Racing 15x10 Outlaw II's, 33" Dynapro M/T's" ,Optima Battery, TeamRushed + Summit Racing CDI ignition, FlowKooler water pump, Edelbrock Performer Intake Manifold, Holley 4160 390cfm, Herculiner, Silver Ceramic Coated Hedman Hedders, Flowmaster 40's.
Warn PowerPlant HD 12K Winch, Dirtworx front and rear bumpers.