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#30903 11/03/2003 10:54 PM | Joined: Aug 2003 Posts: 106 Shop Shark | | Shop Shark Joined: Aug 2003 Posts: 106 | I've been told that there is no need to buy expensive highway-gear swap kits for your closed drive 1954 and earlier Chevy/GMC truck because you can use an open drive pumpkin from a 55 and later GM. Could it be true? Do the open and closed pumpkins interchange?
"I always win." Working mainly alone I do not let my trucks win a war. Maybe a battle here and there but never the war.
Robert
55.1 GMC 450 COE
51ish GMC Suburban
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#30904 11/04/2003 1:08 AM | Joined: May 2000 Posts: 234 Shop Shark | | Shop Shark Joined: May 2000 Posts: 234 | Not quite correct. To clarify, the pumpkins swap only for the 3/4 ton trucks - which have always been open driveline.
No such luck for the closed driveline, you still need to go with the expensive swap kits.
-Boyo
'48 Willys CJ-2A / '55.1 Chevy 3600 / '66 Austin-Healey 3000 / '04 Volvo wagon (parenthood!?)
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#30905 11/04/2003 3:28 AM | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | I hate to disagree but I have installed the center section from 55-62 1/2 tons into 40-54 1/2 ton axle housings many times. They even use the same axle splines. The standard ratio is 3.9 which is not that much better then 4.11. There was a 3.7 option starting in 58 but it is rare. The auto ratio was 3.38 which Patricks reproduces. You will also need to remount the housing to the springs with solid pads.
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#30906 11/04/2003 4:02 AM | Joined: Feb 2001 Posts: 1,897 Member | | Member Joined: Feb 2001 Posts: 1,897 | Thank 68 Dave for mentioning that the rear centers do swap and that the rear axle housing will need pads on it to mount to the leaf-springs. The torque-tube rear ends get some of their rotational resistance strength from the torque-tube itself and did not need the spring pads.
There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!
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#30907 11/04/2003 4:49 AM | Joined: Oct 2001 Posts: 194 Wrench Fetcher | | Wrench Fetcher Joined: Oct 2001 Posts: 194 | You can put the later pumpkin in the torque tube housing with out changing the spring mounts. Just weld the mounts solid so they cant pivot and away you go. | | |
#30908 11/04/2003 5:35 AM | | Anonymous Unregistered | | Anonymous Unregistered | Anybody know the rearend ratio of a 62 GMC suburban with 3-on-the-tree and V6-305? | | |
#30909 11/04/2003 6:14 AM | Joined: Feb 2001 Posts: 1,897 Member | | Member Joined: Feb 2001 Posts: 1,897 | Most likely it will be a 3:73, 3:90 or 4:11
Pull the rear cover and count the teeth or look for the numbers on the outer surface of the ring gear to be sure.
There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!
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#30910 11/05/2003 6:41 AM | Joined: Feb 2003 Posts: 452 Shop Shark | | Shop Shark Joined: Feb 2003 Posts: 452 | I was wondering if an easier(?) way to go open drive rear with the stock trans would be to find the front section of a 3/4T driveline and fit it in somehow. The stock 1/2T open driveshaft would have to be shortened, but the 3/4T set-up does go from closed to open (right around the back of the cab). Of course the rear axle will have to be hard-mounted to the springs. And there would be the problem of matching all the u-joints. Other threads say that isn't too difficult.
Current fleet (subject to change w/o notice) \'49 GMC 3/4-Ton , 60 Austin Healey Frog-eye Sprite (some assembly required), 2011 Dodge Avenger, 2015 Jeep Cherokee. No, they don't all run. My other ride is a (B737)no, (B767)no, A320.... Update... was Embraer E190, now Boeing B787. Knowledge is a wonderful thing, but ignorance means you don't know you can't do something.
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