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Quad Box Trans


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it will bolt up with the flywheel housing and the trans mounts but i dont know about the driveline work the quad box is a long trans. if you are close enough to eastern ky that shiping wouldnt kill you i have 2 that i would sell 1 for parts it has a chiped tooth on the big gear in the back of the main box and needs a bearing kit. the other one is still in the truck it workes good but has a whine in high split 5th thats loud it might need bearings in the back box. im going to put a 6speed in my truck because i have to hire a driver for it and not many people knows how to drive a quad box any more. plus the 6speed will handle the tork better than the quad for what im doing with the truck. joe

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It'll fit, you'll have to shorten the driveshaft because the back box on a quadruplex is a lot longer than the duplex.

Also, make sure what type of clutch is in your truck. In a B model it will have either a push type single disc clutch, or a push type double disc clutch, you have to find a quad box with the correct bellhousing, input shaft etc to work with the type of clutch you have.

Regarding the trans from Joe's Mack, I'm not sure what year his DM600 is, but unless it's a very early one, the DM's usually had the pull type double disc clutch setup.

You could possibly mix & match parts from the front of your Duplex main box to make it work if it's set up for a different type of clutch than yours, or change your clutch & flywheel to match, but if you go from single to double disc you'll have to redrill the frame to move the trans mounts about an inch, and also if you go to a pull type clutch in your B model, you'll have to re engineer the clutch linkage to pull instead of push on the throwout bearing.

Edit: I see Joe's Mack DM is a 1969, so that would almost certainly have the pull type double disc clutch.

"If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

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hi guys my b-61 has a duplex, i was thinking of putting in a quad box,how hard is it to find one,and how much do you guys think it will cost,also will i have to do any driveline work to make it fit,thanks

hey i have one in a 71 dm 600 that i am scrapping, if you want it let me know soon.


We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful.

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