Rear End ID ?'s - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72 Cheyenne K20 · 06-10-2005, 12:36 AM

I know this is probably a stupid ?, but I can't find any info on the net anywhere. I have a stock 72 3/4 ton 4x4 w/ no posi. First off how do you tell what rear end you have. I am assuming it is either an Eaton HO52 or HO72. Does this sound right and how do I tell which one it is? Now, do they or did they ever make a posi for this rear end. I would like to take my truck to work every now and then and my drive is about 60 mile on the interstate. I found a site with a gear ratio calculator and figured I need gears in the low to mid 300's to run 70 MPH at 2600 RPM's with 33" tires. I thought I read in a post a while back that the posi only came in 411's or higher, is that true?

Thanks for the help, Scott

Americanrider · 06-10-2005, 01:34 AM

Yessir, 4.10 or 4.56 rears for the Eatons. They did make a posi, I have seen them here on the board once in a while.

06-10-2005, 12:36 AM	#1
72 Cheyenne K20 Registered User Join Date: Feb 2003 Location: Staunton, Virginia Posts: 554	Rear End ID ?'s I know this is probably a stupid ?, but I can't find any info on the net anywhere. I have a stock 72 3/4 ton 4x4 w/ no posi. First off how do you tell what rear end you have. I am assuming it is either an Eaton HO52 or HO72. Does this sound right and how do I tell which one it is? Now, do they or did they ever make a posi for this rear end. I would like to take my truck to work every now and then and my drive is about 60 mile on the interstate. I found a site with a gear ratio calculator and figured I need gears in the low to mid 300's to run 70 MPH at 2600 RPM's with 33" tires. I thought I read in a post a while back that the posi only came in 411's or higher, is that true? Thanks for the help, Scott Attached Images Last edited by 72 Cheyenne K20; 06-10-2005 at 12:37 AM.

06-10-2005, 01:34 AM	#2
Americanrider Registered User Join Date: Dec 2004 Location: NW, WA. Posts: 1,421	Yessir, 4.10 or 4.56 rears for the Eatons. They did make a posi, I have seen them here on the board once in a while. Last edited by Americanrider; 06-16-2005 at 01:09 AM.



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