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Enlighten me on the variations of R model hoods. I have a 79 r686st that the back of the fender is a seperate part bonded to the rest of the fender, and a 1981 hood that is all one piece but has a fake seam where the 79 has that bonding. Bought an 88 that probably has an aftermarket hood, and have a 95 with the new style hood. Why the variations on the 79 and 81?

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I believe the 88 doesn't have any "bump" where the 79 and 81 do.

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If I recall right when the mack 300 with front mount intercooling was introduced they added a extra inch or 2 to the hood. this was around 81' 

 

early R models had a body line at the back of the fender. this went away some time in the mid 70s?

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Posted (edited)

You can see the seam I'm talking about in these pictures. The truck is the 79, and the hood on the ground is the 81. The 81 went to the scrap yard years ago, except for hood, engine, trans and rears.

Both trucks, 79 and the 81, were/are engine mounted intercoolers, endt676 engines.

The 81 was a Canada truck, not sure where it was made.

KIMG0298~5.JPG

KIMG0288~2.JPG

Edited by JoeH

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This topic came up a few years back but I can't find the thread. I seem to remember someone saying that the hoods were not necessarily made by the same manufacturer so the differences were down to the particular process employed by each manufacturer.

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Interesting, because my flatback R cab doesn't have the seam body line at the back of the fender, and it's the oldest truck we have.

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All the early flat backed cab R's I have seen had what looks like a one piece hood without  the fender seam. I think Mack may have started getting the hoods from a different supplier sometime in the 70's and their manufacture process involved bonding on the fenders so for this reason the seam became a feature. Perhaps because it was quite distinctive it was kept for a while when they switched back to single piece hoods. It would be interesting to know if Mack used more than one supplier at the same time and had both variants available.  Later R model hoods didn't have the seam or that slight step in further down the fender either. I suppose Mack just decided to clean up the design a bit.

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