can someone on here DECODE my protect-o-plate ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

19673ontree · 06-25-2009, 05:58 AM

I'd like to know for sure what rear end ratio my 67 came with , I have the original protect-o-plate with the truck from when it was new and I know those code's are on there , it will have a code that will tell if it's a 3.73 or 4.11 , if anyone can do this I will post it this evening , thank's ,,,,,

tcb-1 · 06-25-2009, 06:42 AM

I believe the protect-o-plate has the rear end code stamped in. post up a pic when you have a chance. I'll try to decode it tonight.

Longhorn Man · 06-25-2009, 11:10 AM

i'm pretty sure the 4.11 only came in over drive trucks (1/2 ton) and you should have a 3.73 gear.

roger0080 · 06-25-2009, 06:56 PM

Your POP will list the rear axle build code, ie that is a Chevrolet axle, the build month, build day, and the plant. The build code doesn't include the gear ratio.

On a 1967 GMC POP I happen to have, that _does_ have the axle ratio embossed on it, seperate from the axle build code, but not the Chevrolet POP's apparently.

If you would have had the 3/4T or 1T Eaton axle in it, the 3rd member would have the axle ratio code stamped on it; else the gear ratio would be on a metal tag on the differential cover, but that's probably gone by now.

If you still are out of luck, you can jack it up and spin the wheel and count wheel rev's to pinion rev's, do the math and come close the the axle ratio w/o pulling the diff cover.

factorystock · 06-25-2009, 07:22 PM

Good technical question. Protecto plates and build sheets were the only positive way of matching the vin # with the powertrain combo. For 1967, HB is 3.07, HA,HC,MD is 3.73, HD, JQ is 4.11. Remember Protecto Plates were stamped backwards so they came be pressed in ink to be transferred to an invoice.

06-25-2009, 05:58 AM	#1
19673ontree CAN'T FIX NOTHIN Join Date: Sep 2006 Location: SOUTHRUST VIRGINIA !!! Posts: 2,112	can someone on here DECODE my protect-o-plate ? I'd like to know for sure what rear end ratio my 67 came with , I have the original protect-o-plate with the truck from when it was new and I know those code's are on there , it will have a code that will tell if it's a 3.73 or 4.11 , if anyone can do this I will post it this evening , thank's ,,,,, __________________ 1967 C10 Shortbed Fleetside Small back glass 6 cyl 3spd on the tree 3.08 gears underdash AC

06-25-2009, 06:42 AM	#2
tcb-1 Nothing to see here..... Join Date: Jun 2007 Location: Shawnee, KS Posts: 4,625	Re: can someone on here DECODE my protect-o-plate ? I believe the protect-o-plate has the rear end code stamped in. post up a pic when you have a chance. I'll try to decode it tonight. __________________ Doug THANK YOU to our American Soldiers & Veterans - POW MIA "You will NEVER be forgotten". The democracy will cease to exist when you take away from those who are willing to work and give to those who would not. Thomas Jefferson

06-25-2009, 11:10 AM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: can someone on here DECODE my protect-o-plate ? i'm pretty sure the 4.11 only came in over drive trucks (1/2 ton) and you should have a 3.73 gear.

06-25-2009, 06:56 PM	#4
roger0080 Registered User Join Date: Nov 2000 Location: Carver County, Minnesota, USA Posts: 626	Re: can someone on here DECODE my protect-o-plate ? Your POP will list the rear axle build code, ie that is a Chevrolet axle, the build month, build day, and the plant. The build code doesn't include the gear ratio. On a 1967 GMC POP I happen to have, that _does_ have the axle ratio embossed on it, seperate from the axle build code, but not the Chevrolet POP's apparently. If you would have had the 3/4T or 1T Eaton axle in it, the 3rd member would have the axle ratio code stamped on it; else the gear ratio would be on a metal tag on the differential cover, but that's probably gone by now. If you still are out of luck, you can jack it up and spin the wheel and count wheel rev's to pinion rev's, do the math and come close the the axle ratio w/o pulling the diff cover. __________________ 72 Chev C-10 90% restored (former AZ truck) ... 71 Chev K-20 Cheyenne my vacation crusier... 72 Chev C-10 Now retired and striped after many faithful miles... 72 GMC 1500 Retired to the junk yard after bought new in '71...

06-25-2009, 07:22 PM	#5
factorystock Registered User Join Date: Feb 2007 Location: west coast Posts: 3,358	Re: can someone on here DECODE my protect-o-plate ? Good technical question. Protecto plates and build sheets were the only positive way of matching the vin # with the powertrain combo. For 1967, HB is 3.07, HA,HC,MD is 3.73, HD, JQ is 4.11. Remember Protecto Plates were stamped backwards so they came be pressed in ink to be transferred to an invoice.



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