T56 Trane mods
Vipers are the better ones. However before 08
In 08 they switched to the tr6060 with remote shifter. It can be adapted though.
Ebay viper transmission
There are bellhousings for mopar to the ls style t56. Never seen one for the slant 6 though.
Also keep an eye on gear ratios. The .5 overdrive may be too extreme.