Can I install a new fuel sender unit on a 72 duster without removing the tank?

I just now looked at your avatar and realized the car we're discussing. As in the other thread I mentioned this in, I am almost 100% certain this car belonged to a member here. Did you ever determine that?
Not yet. I've sent the dealer I bought the car from my contact information to pass onto the previoius owner. I'm hoping that this person will contact me.