However, as my chassis is Z'd, the center of the rearend pinion sits just above the top of the chassis 'rails, meaning the output shaft of the transmission will be at the same height. This put it exactly where the center spacer plate and the middle of the cross tube were intended to be. Normally the rear of the trans would mount below these. With the chassis (and jig!) turned upside-down, I removed the center of the cross tube, placed it at the rear of the central gap, and clamped it and the spacer plate to a length of angle placed across the underside of the side 'rails. With a little trimming of the curved section of the plate, this will allow me to remove my trans from under the car should the need arise. A little forward planning goes a long way if you intend to keep a car for any length of time!