Thread: More 37 Dodge Pickup Parts?

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With the decision made to use the Dana and 4.56s I spent a good part of yesterday researching Chrysler’s 518 OD transmission. I’m pretty happy with what I found out.

Basically it’s a 727 with an additional planetary attached for the OD function. The OD (and lockup) is electrically controlled, and the transmission itself is shifted with basic 3 speed shifter.....meaning I don’t have to redo the column shifter I already built, although now I’l leaning to a floor shifter. There is also a kit available to retain the automatic OD/Lockup functions without the computer that’s under $100.

Apparently the 518 are strong enough as is unlike the early 700R4s. I am told there are potential problems with the lockup convertor but if it’s disengaged for all but highway use they do OK. The big plus is with the 4.56s and .69 OD the effective ratio is 3.15.

The down side for this project is the size of the OD unit, which is considerably larger than the stock extension housing of the standard 727. Fortunately I only got as far as templating the floor in cardboard, so It’s no big deal at this point. I’m thinking about looking into a pre-fab transmission tunnel at this point anyway.

I took a trip to my friends transmission shop today and he set me up with a bare case so I can see how it will work out. You can see the difference in size of the extension housing on a 727 and the OD unit on the 518.

On a side note I also ordered a flip top gas cap to the keg today........just in case.