Yes, it should have the HD trans

you would be better off buying the whole motor out of that wrecked GP. save your self the time and money of converting the NA to a SC. The GTP tranny should be the same as a SSEI tranny but not at tough as ur SE tranny

The GP trans doesn't mount the same as ours so you will need a bonneville trans or upgrade yours. i have an upgrade kit for the SE trans sitting here if ya need it

The SE trans is not an HD, that last statement is wrong. On which way is better top swapping or motor swapping, that depends on the person doing it. A top swap can make a lot more power, and requires much more tuning and a watchful eye. A motorswap will be the same as all other L67 motors.

Many of the W body transmissions do have the webbing on the back. Other things like year and compatibility are bigger factors. However many of the trans casings will have the webbing and 3 bolt holes we need in our H bodies.