[greg64]

Also, now that you have the driveshaft out anyway, check the u-joint condition, and grease them up.

And (you knew there had to be more) is your engine an original 74, or is it possibly newer? If you can see the crank flange, if its bolt circle is 3.58" it's pre-86 and uses the two piece seal (easier to change). If its bolt circle is 3", then it's the later engine and a one piece seal.