Has anybody got some friendly advice about how to fix what started out as a faulty odometer and soon after the speedometer. I took it to a speedometer shop, who did not fix it, now the temp and fuel gauges don't work either and the battery light is on and the overdrive switch seems to be working backword. I switched out the instrument cluster (from later 240 models) two times, but did not help.

Could well be a rotten wire harness. Hopefully not!

Make sure you DON'T (and didn't) hook up the red and white wire that is located behind your insutrument panel - unless you have a tachometer.

This carries a high-voltage signal pretty much directly from the ign. coil to a tachometer, if you have one or put one in later.

If you hook up that wire anywhere else on the back of the cluster, lots of stuff will fail. I made that mistake once.

Also make sure the small wire at top rear of alternator is intact, as well as the small ground at about 8 o'clock on alternator rear and the heavy red (batt. +) wire at rear of alternator.

OD light should go on when you defeat the OD using shift-lever button.
Should stay off when OD is enabled, regardless of what gear is in use.
Car starts w/OD enabled by default, unless there is a problem w/OD system.
Plenty threads on OD issues on this board!

How is your engine wire harness? crispy? check that out...