# Mack Transmission?



## denick (Feb 13, 2006)

We have a 1978 RD686SX with a 6 speed transmission. 2 stick type. Today it seems the main shaft went. Does anyone know of a used or rebuilt transmission?

I had thought of putting a 12 speed Mack airshift transmission in the truck if the transmission needed work. Anyone know of a 12 speed out there?


Thanks

PS the 45 ton wrecker that came out blew a drive shaft while trying to back down the dirt road we were on!


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## Joasis (Mar 28, 2006)

Well Nick, if you lived in Oklahoma, you could have your pick..the old R models were the mainstay of a lot of oilfield companies here, and there are a lot of parts trucks around. I would not be surprised if you called Enid Mack Sales, they would have a line on a tranny for you. http://www.macktrucks.com/EnidMackSalesInc/


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## tgeb (Feb 9, 2006)

I don't have a clue Nick, sorry.


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## cexcavation (Apr 17, 2008)

My advice is to shove a 12speed in there and smile every time you drive the thing from then on:clap: I used to drive my Dad's Superliner with the 12speed behind a 350horse Mack. I have heard of failure issues behind high horsepower combinations, but never had an issue with that tranny-ran down the road at 54,600lbs. Another Mack guy I know swears by them as well. They are a slick tranny for dump trucks.........5 or 6 gears in reverse:thumbsup: Easy to shift, etc. etc. My dad had an old B model Mack with the Twin sticks. A driver somehow managed to get the thing locked between two gears. Dad had to crawl under and pop the linkage with a bar or somethin like that to get her freed up.......ran fine thereafter.


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