... assuming the donor car had the correct speedo or diff in it, is not a perfect solution.

but if you had the vin for the donor car, you could find out.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

That's what I thought, which is why I was puzzled by the wide variations in the numbers. The speedo basically measures the RPM of the drive shaft, right? That would make it independent of the tranny, but dependent on the diff ratio.

Per the link, the 3.07 diff probably came out of the TD (it was the only 3.07 I saw), so a TD speedo with factory diameter tires ought to make it closer; unless there's also some mechanical slippage or something in the tranny/cable/speedo connection.

I took apart the cluster again, lubed up the speedo (125 MPH, from a 9/82 300TD) input and adjusted the needle. Now it appears to be ~5 MPH too low at all speeds, good enough for me.