The odometer and tripometer in my 89 Formula have never worked, speedo works fine. Just picked up a 91 speedo. Will it work and be basically a plug and play in my 89? I haven't taken the old one out yet so I can't compare the guts of them yet. The 91 is a 120 mph and it is a 6 digit odometer.

Thanks in advance,

 

Should work as long as the max speed is the same in both and it came out of an V8 and going to a V8.

 

My 89 has the 140 mph speedo. If I can't swap the entire speedo, do you think I could take the odometer out of the 91 (120 mph) speedo and swap it into my 89?

 

You can swap it out, but it may not give you an accurate speed reading. If the odometer is the same part should work.