That Buick makes nearly 500 foot pounds of torque and isn't real heavy compared to the original motor.
Instead of using a divorced case why not eliminate the tailshaft and short driveshaft by marrying the transfer case to the TH400. That would solve the other concerns.
I've seen a nailhead in a 1-ton but don't at the moment ever recall seeing the newer big Buick in one of these trucks.
