So, I take it that's not your transmission in the pictures? There is obviously a spacer between the bellhousing and the trans case, and the logical thing to do is to add a plate at right angles to it to bolt the pedal bracket onto. Them use angled braces to the front and rear over to the frame to reinforce the pedal mount. Those braces will need to have rubber vibration isolators to prevent transferring engine noise to the frame and cab.
David, the original pedal assembly was bolted to the bell housing, so there won't be any more movement of the pedals than it had when the truck was new.
Jerry
