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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!
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#35571 02/01/2004 6:54 AM | Joined: Feb 2003 Posts: 58 Shop Shark | | Shop Shark Joined: Feb 2003 Posts: 58 | I have a 56' 1/2 ton rearend that I am considering putting in to one of my other trucks and change the gearing in it.
I am interested in changing it into either my 51' chevy 3/4 ton which has a 4.90 gearing or my 49' 1 ton with 5.14 in it.
I also want to change the front to a six bolt and need to know if there is anything I can put right on the axle.
If I can change the rearend I hope to put a T-5 tranny in with it.
I think this would make it easier on the engine if I can do all this.
Collecting is fun, as long as momma enjoys riding in them.
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#35572 02/01/2004 7:33 AM | Joined: Apr 2002 Posts: 1,571 Shop Shark | | Shop Shark Joined: Apr 2002 Posts: 1,571 | You can get a '68-'72 center section that will fit the 3/4 and 1-ton axles (provided that they are not torque-tube axles). These had an optional 4.11 gear ratio. They were often found in trucks with automatic transmissions, but mine came from a 4-speed truck. It might be another option to consider. If interested, search the archives as this swap has been discussed several times. | | |
#35573 02/01/2004 7:49 AM | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | The standard ratio for 55-62 1/2 ton is 3.9. There were 4.11,3.7,3.38 optional ratios also.
See the USA in your vintage Chevrolet! My Blog | | |
#35574 02/01/2004 8:15 AM | Joined: Feb 2003 Posts: 58 Shop Shark | | Shop Shark Joined: Feb 2003 Posts: 58 | How should you be able to tell which it is?
Collecting is fun, as long as momma enjoys riding in them.
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#35575 02/01/2004 5:33 PM | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | Divide the number of teeth on the ring gear by the number of teeth on the pinion. A 3.9 will have 39 on the ring and 10 on the pinion.
See the USA in your vintage Chevrolet! My Blog | | |
#35576 02/01/2004 6:42 PM | Joined: Jul 2003 Posts: 252 Shop Shark | | Shop Shark Joined: Jul 2003 Posts: 252 | The pinion gear will also have a date code, and the number of teeth stamped right into the top of it. The pinion in my 61 Apache has GM 11-60 39-10 and a part number stamped in it. The 39-10 being the tooth count for the gear set. | | |
#35577 02/04/2004 8:57 PM | Joined: Jan 2004 Posts: 288 Shop Shark | | Shop Shark Joined: Jan 2004 Posts: 288 | Hey, would anyone know the standard gear ratio on a 55 first series? I have a 68 camaro 283 small block with a 4 speed borg warner transmission. I am assuming that I have the original truck rear end. I would like to go to a lower gear but am not sure what gear ratio I have. Truck is in storage right now and I won't be able to get at it till this spring.
thanks,
Chris
Chris 1955FirstSeries
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