Join Date: Jan 2015
Location: Injun Territory, 'Merica!
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the nodular center cast housing along with axle tubes should be a finished interpretation of natural steel, then misted from the rear cover side and below with chassis black. On top of the center housing right above the pinion flange their will be a good sized color splash notating the ratio. Sometimes this color splash is under the center hsg. If your car is out of a low volume Pontiac A body plant, and you are 100% sure the rear is original to the vehicle, and the date assembled in the axle tube is several months before the assembly date of the car, you can assume the assembled rear sat for quite some time in a rack, & it's a good possibility the rear was liberally painted with a chassis black before being put in the transportation fixtures to be shipped from the Pontiac MI axle plant to the cars final assembly plant.
The rear cover bolts, personally, I have finished in a clear zinc but they get black paint on them in the mist treatment. Have also had them plated in black phosphate. In my opinion, nothing looks worse (out of place) on a GM rear axle in a very high point restoration, than freshly plated shiny rear cover bolts.
Placement of the alum limited slip tag is off the rear cover bolt at the near 5 o'clock position. often times the aluminum posi tags on the 60's and 70's Pontiac 8.2's and later 8.5's were rolled upwards and outwards and the misting process of the black paint covered the back side of the limited slip tag. Once the original owner or dealership help was about to remove the rear cover for the first time and drain the rearend grease, the tag was bent downward to access th Bol head, & one could read the raised text on the tag. On the colored stripe type tags available in the $35 "detailing" tag kits, the colored band style tag wrapped around the axle tubes, denoting axle ratio and code, I've never seen one on a 69-72 10 bolt, or evidence of one on an extemely low mile original car, and one of my parts cars was a garaged since 1972 4,000 mile '72 Lux LeMans. Bought that particular car in '99 and not only could one eat off the bottom of the car, along with it having a few paper tags on it, there was no evidence of any colored stripe style tag around the axle tube.
On the original rear brake drum mounting face there will be a off white with red letter square gummed label denoting the rear axle code. On the McKinnon 12 bolts used in '70-72 455 Pontiac A-body's, they did not come with the off white with red lettered gummed ID labels, but instead had the two letter axle code stenciled in flat yellow paint onto the mounting flange of the drum. No stripe tags around the axle tube either. Only mention this detailing of the '70-72 McKinnon built 12 bolts, as the $35 decal detailing kits provide "made up" ID stickers for the McKinnon 12 bolts. Having been under quite a few low mile garaged '69-72 Pontiac A body's and F body's, and examining all the detail tags that come on one of the $35 detail sticker sheet, just one of those things that makes one go Hmmmmm. Hope this helps.