Thanks for the reply jozsefsz! Good...that tells me the units come "set" for the car (which it should be) and no modifications need to be made. My mechanic did not have the necessary specs to test the unit against. But, I found them in the 1975-1976 Shop Manual. There is also directions for testing the unit in the manual. Unfortunately I am not a "hands on guy", so my experience is almost zero. But I can read a tech manual. We will likely order a new sending unit. (I believe I ordered mine online from auto zone.) We will test the unit before removing the old and installing the new. Thanks for the info on testing the gage. That should be helpful, but the mechanics may know that. Anyway thanks for the reply.
As a side note....I'm a Buckeye also, from Caldwell. It is a small town between Cambridge and Marietta just off Interstate 77. That is where my Mother bought the car off the showroom floor at Caldwell Motors November 30, 1974.