1/2 ton ton 3/4 conversion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

403oldsman · 01-01-2007, 07:04 PM

My brother is wanting to convert his 78 1/2 ton swb 4x4 to a 3/4. He already has a front axle and want to use a 14b for the rear axle. My question is what will it take to convert the rear from a 12b to 14b. Does this require a "trick u joint".
thanks
Mark

b454rat · 01-01-2007, 07:32 PM

If you get a rear out of a 70s 3/4 ton, that part will bolt in. Might need to get a conversion joint, but I've seen 12b's with a 1350 on them. Shock mounts may have to be moved too.

Joe Gribben · 01-01-2007, 08:34 PM

yes to convert 1/2 to 3/4 the rear drive shaft joint is a special one go to your local napa dealer the will have them i will try to find the part number.

soleeagle · 01-04-2007, 12:42 AM

When I did my suburban I went to Advance Auto Parts to get my U-Joint

Part # 21153 for $22.88

jacobs · 01-08-2007, 06:57 PM

When I converted from 1/2 ton to 3/4 ton on my 1970, I had my driveshaft shortened and installed the correct 3/4 ton yoke. By using the correct u-joint, it's much easier to get a replacement when needed and cheaper. The nose of the 3/4 ton differential is longer than the 1/2 ton.

01-01-2007, 07:04 PM	#1
403oldsman Registered User Join Date: Mar 2005 Location: Van Horne, Iowa Posts: 46	1/2 ton ton 3/4 conversion My brother is wanting to convert his 78 1/2 ton swb 4x4 to a 3/4. He already has a front axle and want to use a 14b for the rear axle. My question is what will it take to convert the rear from a 12b to 14b. Does this require a "trick u joint". thanks Mark __________________ THERE is NO REPLACEMENT FOR DISPLACEMENT 1971 CHEVY 4X4 4SPD 406 CHEVY Lockers front and back 1978 BONNEVILLE 403 OLDS 1985 K1500 F5L912 Deutz Power (work in progress) http://67-72chevytrucks.com/vboard/s...d.php?t=389561 1963 Oliver 1600 diesel 1956 Oliver Super 88

01-01-2007, 07:32 PM	#2
b454rat Senior Member Join Date: May 2004 Location: Binghamton, NY Posts: 3,464	Re: 1/2 ton ton 3/4 conversion If you get a rear out of a 70s 3/4 ton, that part will bolt in. Might need to get a conversion joint, but I've seen 12b's with a 1350 on them. Shock mounts may have to be moved too. __________________ 2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 4” SAS 1999 GMC Yukon 350/4L60 6" SAS

01-01-2007, 08:34 PM	#3
Joe Gribben Registered User Join Date: Aug 2006 Location: Wabash, Indiana Posts: 100	Re: 1/2 ton ton 3/4 conversion yes to convert 1/2 to 3/4 the rear drive shaft joint is a special one go to your local napa dealer the will have them i will try to find the part number.

01-04-2007, 12:42 AM	#4
soleeagle Registered User Join Date: Sep 2003 Location: Shelbyville, Indiana Posts: 614	Re: 1/2 ton ton 3/4 conversion When I did my suburban I went to Advance Auto Parts to get my U-Joint Part # 21153 for $22.88 __________________ Chuck '85 Chevy Silverado 4X4 '91 Chevy 4X4 Suburban http://www.cardomain.com/memberpage/545941

01-08-2007, 06:57 PM	#5
jacobs Registered User Join Date: Sep 2005 Location: 9000' Mountain Man Posts: 326	Re: 1/2 ton ton 3/4 conversion When I converted from 1/2 ton to 3/4 ton on my 1970, I had my driveshaft shortened and installed the correct 3/4 ton yoke. By using the correct u-joint, it's much easier to get a replacement when needed and cheaper. The nose of the 3/4 ton differential is longer than the 1/2 ton.

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