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| | | | Joined: Jul 2008 Posts: 50 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2008 Posts: 50 | I have a 1970 GMC 3/4 ton with a three speed transmission, I am wanting to change it to atleast a four speed or maybe even a five speed transmission. What would be the best transmission for this aplication? Where can I get one for this truck and would it mount up to the origenal bell housing? The truck has a 350 in it so I thought it might be an easy swap out.
1949 Chevy 4400 GrainbedIn the Stovebolt GalleryPhotobucket picturesThe taxpayers are sending congressmen on expensive trips abroad. It might be worth it except they keep coming back! Behind every successful rancher is a wife who works in town.
| | | | | Joined: Oct 2003 Posts: 5,152 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Oct 2003 Posts: 5,152 | How do you intend to use the truck? Transmission choices affect usability and drivablilty and need to match your intended use.
1955 1st GMC Suburban | 1954 GMC 250 trailer puller project | 1954 GMC 250 Hydra-Matic | 1954 Chevy 3100 . 1947 Chevy COE | and more...
It's true. I really don't do anything but browse the Internet looking for trouble... | | | | | Joined: Jul 2006 Posts: 40 Shop Shark | | Shop Shark Joined: Jul 2006 Posts: 40 | An SM465 - 4 speed from that same year would bolt right in | | | | | Joined: Jul 2008 Posts: 50 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2008 Posts: 50 | I intend to do moderate hauling with the truck nothing to heavy. I forgot to mention that my truck has a automatic transmission. Was there an automatic 4 speed?
Last edited by 49' Hayhauler; 12/22/2008 3:59 AM.
1949 Chevy 4400 GrainbedIn the Stovebolt GalleryPhotobucket picturesThe taxpayers are sending congressmen on expensive trips abroad. It might be worth it except they keep coming back! Behind every successful rancher is a wife who works in town.
| | | | | Joined: Jan 2008 Posts: 4,961 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,961 | If you want to go from an automatic to a standard, the best thing to do is to find a parts truck of the same vintage with the desired transmission. That way you will have a clutch, linkage and etc. | | | | | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | | | | | | Joined: Jul 2006 Posts: 40 Shop Shark | | Shop Shark Joined: Jul 2006 Posts: 40 | Now you're talking a different tune. Go to a 700R4. You will need a different torque convertor, will probably have to cut the driveshaft,and you'll need to install a switch to lock up the convertor. My suggestion is to find a 88 or newer 700R4,as they have a solenoid in them to give them a more positive shift. | | | | | Joined: Jul 2008 Posts: 50 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2008 Posts: 50 | It is sounding like it might be easier to go to a manual 4 speed or just stick with the three speed auto. Which would you recomend? I am not planning on doing much highway driving and if i do I am only going 60 in this truck. I could live with the three speed just thought there might be a four speed for this year of truck.
1949 Chevy 4400 GrainbedIn the Stovebolt GalleryPhotobucket picturesThe taxpayers are sending congressmen on expensive trips abroad. It might be worth it except they keep coming back! Behind every successful rancher is a wife who works in town.
| | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | Stay with the auto that's already in it, it's mnuch stronger than a 700r4. Or is you do want to upgrade to an overdrive automatic, take a look at the 4L80E, which is the overdrive equivalent to the TH400 that you already have. Another option would be a gear change. Being a GMC, you should have a Spicer 70, whcih has very good gear availability if you want to change the ratio (3.55-3.73 would be a good range).
Bill Burmeister
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