Manual transmission and the flywheel in the truck will not bolt to the 606. 61X and 60X have entirely different bell housings. You'd need a transmission from a 230GE 300GE or 60X 250GD G290 G300D 300GD and the flywheel.

A 190E, 190D, or 300E USA 5speed transmission and flywheel will bolt up to a 606 but I have no idea if they could be adapted to your transfer case.

It sounds like he sent you an engine on a palette, not a donor car. You've got a lot of stuff to make or source at this point.
As mentioned the only way to make it run is the 603T full mechanical IP which should be modified to perform with the intercooled 606T.

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