need driveline parts - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Trucks · 02-29-2004, 04:34 PM

Hi, I bought a 68 GMC 3/4 ton 4x4 with a messed up rear end, when I get over 35mph it makes a nasty grinding noise. Also its 4.56 in back and 4.55 in front, too low for me. SO I figured If I replace both the front and rear with something not so "granny" I can at least do 65 mph I'd be happy. Do you have a diff that will work for me? The truck has leaf springs and I have swapped a whole tube before but not just the rearend. I have not done a front swap at all. Any help would be great!

Also Its second gear wont enguage, synchro ring? Should I repair it or replace it?

If I lifted it the cheapest way, and put say, 32" tires on could I go any faster? I could just replace the rear, same gears if I got big enough tires maybe. I'm in brownton MN

Bowtie67 · 02-29-2004, 07:28 PM

That would be a type4 carrier and you can drop gears down to 3.73 which wouldnt be that expensive just time consuming unless you have someone else do it. not sure what to do about trans, I would rebuild i myself but these can get pricey having some one else do it so it might be cheaper to swapout. JMO

02-29-2004, 04:34 PM	#1
Trucks Is that a Chevy 69...? Join Date: Feb 2004 Location: Brownton MN Posts: 112	need driveline parts Hi, I bought a 68 GMC 3/4 ton 4x4 with a messed up rear end, when I get over 35mph it makes a nasty grinding noise. Also its 4.56 in back and 4.55 in front, too low for me. SO I figured If I replace both the front and rear with something not so "granny" I can at least do 65 mph I'd be happy. Do you have a diff that will work for me? The truck has leaf springs and I have swapped a whole tube before but not just the rearend. I have not done a front swap at all. Any help would be great! Also Its second gear wont enguage, synchro ring? Should I repair it or replace it? If I lifted it the cheapest way, and put say, 32" tires on could I go any faster? I could just replace the rear, same gears if I got big enough tires maybe. I'm in brownton MN __________________ Ahhhh, the wonderful sound of a rumbling V8.

02-29-2004, 07:28 PM	#2
Bowtie67 Registered User Join Date: Jan 2004 Location: NH Posts: 2,266	That would be a type4 carrier and you can drop gears down to 3.73 which wouldnt be that expensive just time consuming unless you have someone else do it. not sure what to do about trans, I would rebuild i myself but these can get pricey having some one else do it so it might be cheaper to swapout. JMO



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