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Labor Day Putting down your wrenches or time for
MORE wrenching? 
Plenty of places to share. | | Click on image for the lowdown. 
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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
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For helping keep this great
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on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Jerry, Will you be looking for an adapter, or do you hope to find a pair of original gears (drive/driven gears) that will work with your SM420? Good luck finding the appropriate drive/driven gears. Here are instructions for a ratio adapter. You can nowadays more easily find your ratio/correction factor by using a GPS to find your true MPH. A ratio adapter can then be made to result in a better speedometer reading.
Last edited by tclederman; 05/29/2015 1:57 PM. Reason: added link to ratio test - oops
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