Advantages of a '76 C20 14 bolt rear in '66 C20 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**JPTL** · 03-16-2026, 04:45 PM

After starting a rear brake job and discovering the new '66 C20 brake cylinder doesn't fit, I've come to realize that my '66 C20 truck has a '75 -'86 14 bolt rear - not by finding the stamp, but by matching up the original brake cylinder.
The truck also has a '76 Chevy 350 and THM350 transplant, so I'm guessing that the p/o had a '76 C20 donor truck.
I'm assuming that the '66 C20 had an Eaton HO52.
Aside from better parts availability for the GM 10.5" 14 bolt, vs. the Eaton HO52, are there other benefits to this swap? Taller gearing?
Thanks!
JP

03-16-2026, 04:45 PM	#1
JPTL Junior Member Join Date: Jan 2023 Location: Catlett, VA Posts: 33	Advantages of a '76 C20 14 bolt rear in '66 C20 After starting a rear brake job and discovering the new '66 C20 brake cylinder doesn't fit, I've come to realize that my '66 C20 truck has a '75 -'86 14 bolt rear - not by finding the stamp, but by matching up the original brake cylinder. The truck also has a '76 Chevy 350 and THM350 transplant, so I'm guessing that the p/o had a '76 C20 donor truck. I'm assuming that the '66 C20 had an Eaton HO52. Aside from better parts availability for the GM 10.5" 14 bolt, vs. the Eaton HO52, are there other benefits to this swap? Taller gearing? Thanks! JP __________________ '66 C20 Custom Cab - Factory AC AZ truck

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