80 4x4 output shaft seal

[croak]

Can someone give me some guidance here. The rear output of the tranny is leaking, is it a simple seal? 

Do I just pull the drive line, pull out the old seal and put in the new one?

My FSM has zero info. 

I’ve replaced plenty of seals, just want to be prepared before I drain the tranny and go for it. 

It’s on an ‘80 Brat if that matters. 
 

thanks in advance.