Replacing Pinion Seal in Differential

[MotoPsyche@aol.com]

My differential is covered with amazing amounts of oil and muck from what 
appears to be a long-leaking pinion seal.  Given that I have removed my springs 
for refurbishing, I'm thinking now is the time to address the seal.  Is it 
possible to replace the seal without withdrawing the axle and differential from 
the car?  Any tips for how to get this job done efficiently, or things to look 
for?

Many thanks!

Bill Stagg
1960 TR3A