Gotcha! I used a couple pieces of angle iron for mine years ago. One piece laid on the floor like an "L", and the other piece attached under the seat like an upside down "L"...(do a set of these on the inside two mounting holes, and another on the outside two). The two vertical pieces should be the same width, such that they can overlap to make a "C"...one "C" inside near the trans tunnel, and one outside near the rocker. You can fine-tune the height using several pairs of Vise Grips until you like the way they sit (height and tilt angle), then weld em together...or drill and bolt em.
Make any sense at all?