Pardon the glare, but here is my first GPS speedometer effort designed (as much as possible) to go with the AD truck design. With this one I had to make a new case for it (I used sheet brass and copied the original). The oddball multi-colored led lights built into this unit were disabled. I think for any future work I'd do some electronic surgery and relocate some components, shrink the thickness of the thing and try to fit it into the stock case. Either that or I may build a garolite or fiberglass case. At any rate, it works, seems accurate, is smooth and quiet, has a permanent overall odometer and a re-settable trip odometer with 4 trip choices. Hookup is not difficult. One power wire, ground back to the mounting screw, power wire to the high beam dot (an led so it won't need replacing) one wire each for left/right turn signal dots (I took the liberty of adding these...since it wasn't to be 100% original, I opted for convenience--also leds) and two wires/plug in connectors for the re-set switch which attached to the nut/bolt holding the ignition switch and hides below the dashboard. The satellite sensor will just sit unseen underneath the dashboard.
These GPS units are copies of the old Speedhut GPS 3 3/8" speedometer (no longer made) which has the proper sweep and limits max speed to 80 mph (sorry...no 90 mph models have been made). The difference between this and the Speedhut version is the Chinese took great liberty with case depth and used some tall capacitors (which may have been for a reason...or they could have simply been cheaper). There are also 120 mph versions of these available and I think they could be adapted to many different circular styles of speedometer. I haven't found one with a 90 degree sweep yet (for those horizontal type speedometer units), but a person could adapt a 0 to 200 mph unit to read 0 to 105mph with a 90 degree sweep.
This is what it looked like before I tore it up and re-imagined it:
https://tinyurl.com/23nk3bzh
