OK, here it goes. I have taken out the speedometer/odometer assembly out of my '75 Dodge Dart with a slant 6, the old needle was bouncing around aimlessly. The odometer did work. The assembly that I would like to replace it with was given to me by the guy I bought the car off of, however, this speedo goes up to 120 mph. My old one oes up to 100 mph.
Also the top of the old speedo reads; prod. 3593138 serv. 3593140 302637 mile.
The new speedo reads prod. 3592183 serv. 3592186 301659 mile.
Does anyone know what all this means, and will my speedometer be acurate if I replace it with the one that goes up to 120 mph??
I know this is wordy, but if anyone can answer this one it would be greatly appreciated.
Thanks in advance,
Dennis

Change it. It will work fine. Are you changing just the speedo head, or the whole instrument panel? There are some subtle differences in the "shadowbox" around the gauge face depending on year.

D/W

_________________

If it ain't broke, fix it!

I'm changing out the entire speedometer/odometer cluster. Glad to hear that the speedometer will be accurate. I thought the gearing would be different in a speedo that went up to 120 vs one up to 100. The increments of the mph markings seem different. Thanks for your response.
Dennis

The gearing difference has to do with the final (rear end) ratio and the gear in the trans. This unit will work fine if all that was right to start with.

D/W

_________________

If it ain't broke, fix it!

Thanks for your help. It is now 2:39 am eastern time. Just got the speedometer in. I'll test it out tomorrow.
Dennis