First What do our cars weight. Second What is the differance between the 4t65e-HD and 4t80e. I was thinking it was wierd that a Bonnie GXP with a lower output Northstart motor has a seemingly better trans. Being as GM's trans power handling rating goes up withthe number u know 4L60-4L65-4L80. And what would it take to use one in a GXP. Other than the starter issues.