68 GMC c20 rear question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BurnerBrown · 08-18-2005, 03:10 PM

I believe my GMC has a Dana with 456 gears, not 100% sure of gearing, either way its starting to whine when loaded. I think its the outer wheel bearings.

I am not a big fan of the 62mph top speed, and wanted input about wether to fix the bearings and still have the gearing issue(can I swap in 373s?) or does it make sense to hunt down a new rear? If so, what year rear will fit, I can weld the perch's if need be.

It is a leaf spring rear.

THanks, Bill

BurnerBrown · 08-19-2005, 08:50 AM

Will a rear from a 73-87 truck fit my 68? Width, etc?
THanks

**JIMs70GMC** · 08-19-2005, 11:39 AM

You can get higher gears for a dana60, but their is a carrier split at 4.10 so you'd need a new carrier, if you in fact have 4.56s. Your leaf spring rear should have 42.5" spring spacing so 73 and up rears will fit from a 3/4 ton. The 72 and older 4wd rear will not fit with out moving the perches, same w/ 1 ton rears.

08-18-2005, 03:10 PM	#1
BurnerBrown Registered User Join Date: Jan 2005 Location: Landsale PA Posts: 82	68 GMC c20 rear question I believe my GMC has a Dana with 456 gears, not 100% sure of gearing, either way its starting to whine when loaded. I think its the outer wheel bearings. I am not a big fan of the 62mph top speed, and wanted input about wether to fix the bearings and still have the gearing issue(can I swap in 373s?) or does it make sense to hunt down a new rear? If so, what year rear will fit, I can weld the perch's if need be. It is a leaf spring rear. THanks, Bill

08-19-2005, 11:39 AM	#3
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	You can get higher gears for a dana60, but their is a carrier split at 4.10 so you'd need a new carrier, if you in fact have 4.56s. Your leaf spring rear should have 42.5" spring spacing so 73 and up rears will fit from a 3/4 ton. The 72 and older 4wd rear will not fit with out moving the perches, same w/ 1 ton rears. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

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08-19-2005, 08:50 AM	#2
BurnerBrown Registered User Join Date: Jan 2005 Location: Landsale PA Posts: 82	Will a rear from a 73-87 truck fit my 68? Width, etc? THanks



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