The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

billnorman · 12-22-2010, 04:03 PM

I changed my diff on my '85 from a worn out 3:08 to a 12 bolt 3:40 out of a Big10 I think it was a '78. It's quiet and really zipped the power up but now I need a 700R4 instead of the TH350 to keep the RPM reasonable on the highway. It is indeed a 3:40, I checked it several times, counted the teeth etc. They were made stock by Chev.

12-22-2010, 04:03 PM	#32
billnorman Registered User Join Date: Mar 2009 Location: glen burnie md Posts: 174	Re: My GMC Sierra Grande: Project GOLDIE I changed my diff on my '85 from a worn out 3:08 to a 12 bolt 3:40 out of a Big10 I think it was a '78. It's quiet and really zipped the power up but now I need a 700R4 instead of the TH350 to keep the RPM reasonable on the highway. It is indeed a 3:40, I checked it several times, counted the teeth etc. They were made stock by Chev.