Art Todesco wrote:

I have an approximately 38 year old upright freezer. It is working
perfectly.

In your opinions, would it be advantageous to replace it for a new
more efficient unit? How long do you think it would take it to
pay off?

Your answers can be found he

http://michaelbluejay.com/electricit...igerators.html

It helps to know how the size (in sq.ft.) you have.

A chest-style freezer is more efficient vs an upright style.

And yes, your 38-year-old freezer will be an energy hog compared to a
new unit. You'd probably see a payoff in 5 years for a new chest-style
unit of equivalent size.