Drivetrain Vibration

the picture is a 904 but I can't tell you if those are specific to one or the other. I think both housings have the squared off bit with two mounting holes. These don't all come in the same outside shape however. I measured my hump (tunnel?) and found one that wouldn't touch at any point and still allowed for a little motion. Maybe a longer housing beyond the tranny support might allow for a longer movement radius (???)