lightning has a 4r100 transmission.

I don't think the t56 would work out all that well. For one, I think the 450ft/lb of torque the lightning already makes and it's 4700lb curb weight would be too much for the t56. Plus, think about the shifter. To be able to reach it, you'd need a 30" shifter handle. You'd have like a 10" shift throw.