The parts I have available:

1985 instrument panel with large tach and mechanical speedometer

1988 instrument panel with large clock (not working) and electronic speedometer with broken trip-reset knob.

1985 M46 with port for a mechanical speedometer

1985 rear axle that goes with the above M46

Now... what I WAS planning to do was buy a new mechanical speedometer cable to hook up the 85 instrument panel.

However, after some research with my volvo parts catalogs and wiring manuals, it appears that the 85 axle does have an impulse sensor. It wasn't used for the speedo, but for the gear shift indicator, which lit up if you were driving in the "wrong" gear. According to the parts catalogs from 1985 and 1988, the impulse sensor is the exact same part (1308024-7).

What I'm wondering is, would there be any benefit to using the electronic speedometer instead of the mechanical? Also, has anyone done such a weird mix of parts (85 impulse sensor to drive an 88 speedo) and gotten it to work?

Sidenote: I'm not worried about doing a tach swap or fixing the reset button, those have been well documented on brickboard already. I'm just wondering about the speedometer.

Thanks,

Michel
1979 242DL
1988 244DL