As a point of interest, when Corvette moved the trans to the rear, they too used a variation of planned a four-wheel drive truck transmission. For Corvette, the key element was the stiffness of the bell housing between the engine and the transmission. Corvette too reported that to develop their own transmision would have cost more than the whole C5 development budget. The truck division paid for the tooling for the automatic transmission case with a separate bell housing for both the trucks and the C5. And the C5 was able to use it for a whole year before the truck people released it for their own vehicles.
Long way of saying that this sort of shared development cost and design is a doable thing. However, I don't believe that putting the trans in the rear is as easy a thing for the Viper. According to Mr Ralph, such a design was considered for the Gen V and rejected because to do so would have changed the proportions of the car and therefore the styling icon. I think that's because putting the trans in the rear would have required a lengthened wheel base and moving the cab forward.
So, most probable is, a front mounted automatic variation of the truck trans for the Viper. As another poster suggested, it is possible that the chassis design already has provision for that mounting.
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