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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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| | | | Joined: Jun 2012 Posts: 37 Wrench Fetcher | | Wrench Fetcher Joined: Jun 2012 Posts: 37 | Is this casting number a Saginaw 4 speed? The side of tranny casting number is GM 3781980. It has a granny gear and wondering if there's a swap to eliminate granny and get better gearing for in town and highway use. It appears to be the original transmission. Thanks. | | | | | Joined: Feb 2002 Posts: 12,029 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Feb 2002 Posts: 12,029 | you have the standard SM420 4 speed, usually folks just ignore 1st and use it as a 3 speed .... your choice is go with the original standard 3 speed, no granny, but still 1:1 high, or find an original style OD 3 speed, or switch to a modern OD trans .... or change the rear gears to the [sometimes] available 3.38 ratio
Bill | | |
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