A great deal will depend on who the architect was, who the builder was, and very important, what alloy was used in the construction of the hull.
If it were me, I would contact the owner and get either a picture of the documentation certificate or the hull identification number. Either of those will get you to the builder identification. After several searches, I've come up with nothing related to Yonkers boat building, so I'm assuming it was either sold or went out of business.
If going forward on the purchase, you absolutely need an expert surveyor for aluminum boats. There are all sorts of horror stories on boats with horribly pitted hulls that were filled and barrier coated to resemble pristine hulls. Replating a hull is prohibitively expensive.
Ted