M_Boats: Sounder transducer and knotmeter identification

I hope someone on the list can help me with this: When I got my 1985 M17 last year no electronics came with her, except for the old radio epoxied to the overhead! There is a depth sounder transducer through the hull, and a knotmeter wheel also. Lots of wire, but no identification of make or model that I can find so far. The old owner has been non-responsive. I would love to use them as is, which is to say I am very leery of removing them. But how do I match them to current electronics? Has anyone worked this kind of thing out before? And, yes, I have run aground when I wasn't wanting to. Just a few times. Thankfully the board and rudder both can be raised.