[rpoz11]

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Manganese Phosphate, Zinc Phosphate or Black (cant recall now???)

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Most of the Manganese Phosphate (sp) that I found on the parts off of my Camaros I tore down over the years ended up under painted parts; whether it was pulleys, brake line bracketry, the obvious nuts and bolts throughout the chassis and sheetmetal areas and/or what-have-you.

I cant speak for timeline assembly variations, as we are dealing with months and months of these cars being built as well as suppliers choices at the time.

I just dont see a need to base the Smog Tubes in "MP" prior to any Cad finish I used; and for that matter - as I am no expert on chem plating - I dont know that one would receive the proper finish expected when using any "MP" under a Cad finish plating.

However, I could forsee one bulk assembly of these Tubes seperated for assmebly on the production line, and another bulk assembled for replacement over the counter warranty or replacement needs over time. The latter could have been "MP" based then painted Black to survive the shelf time and weather exposure until they were pulled for use months to years later. Then I could accept the latter idea.

The tubes were raw, assembled and sweated together and were an "eye view" location piece in the engine compartment.

These were mostly in a Silver finish; ie Silver Cad.

Any "MP" finish I found sometimes didnt get the paint on it, like under car locations. It is under my experiences building these cars that several parts were assembled in an "MP" finish without any paint on them prior to installation and some appeared to be ghosted over in that Chassis Black leaving some surfaces painted and some exposing surfaces with just the "MP" showing.