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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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#74348 03/06/2007 8:56 PM | Joined: Aug 2006 Posts: 8 Junior Member | | Junior Member Joined: Aug 2006 Posts: 8 | I have a 49 GMC with stock running gear. SM420 4-speed with the stock rear differential which I believe to be 4.11 - 4.56? I have picked up a good Ford 9" rear axle assembly in good shape but it has 2.75 gears in it. Calculations show with a 27" tire I would be ~2000 rpm at 60 mph. Are these gears to tall for a daily driver with the 4-speed. It has the lowest granny gear I think they ever put in a GM truck? Something around 7:1.
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