My buddy at work lives in the next town east of here. His neighbor passed recently, and used to work on mowers for people. Now, my bud and the decedent's son are going through stuff in the old shop.

Here's what he knows...

-made by Craftsman
-says it is for light duty, whatever it is.

Anyone have an idea as to it's use??

My first guess was piston ring expander! Never used one myself, always used strips of tinplate and three hands! A quick look at google images confirms thats what it is.
Graeme

The general layout looks like a piston ring expander, but the particular shape's kind of odd for that purpose.

yep, that's what it is. I found several like it on google. Thanks guys!!