I have tack welded the engine mounts in place on the frame and then used the engine block/transmission combination to locate the new transmission support. The original rear engine mounting cross member interferred with the transmission housing, primarily the portion housing the slave cylinder/clutch actuator so I removed the center portion leaving the sides that reinforce the frame in the area of the front axle spring mount.
The new transmission cross member was located for/aft by the engine mount locations dictating the engine/transmission location and then the vertical position was determined to give the engine block a 3-4 degree drop to the rear. The transmission cross member brackets needed to be oriented with the longer side horizontal resulting in significant angle disparity between the brackets and the frame, due to the frame taper. I reduced the cross tube engagement with the side brakets to less than 1" to provide more angle flexability to get the brackets tight against the frame. The brakcets needed to be located approx. 2 1/4" above the lower frame flange to achieve the desired engine angle. With all in place the bracket mounting bolt holes were drilled and the brackets mounted. The center section location was adjusted to center the transmission output shaft side to side and then the center section was tack welded to both brackets.
I have measurements for the cab relative to the frame from before the cab was removed and confirmed that the vertical firewall should be located approx. at the rear of the engine block. As I do not have the heads, intake, or distributor in place it's a little hard to confirm clearances but I am fairly confident it should be good. I also checked the shifter location relative to the opening in the cab floor and that looks like it should be good.
Next step is to fully weld in the engine mounts and fully weld the transmisison mount tubes.
I am considering fabricating a means to reinstall the removed original cross member as a bolt in but it will need to be located further back and probably a little lower than the original location.
