Once I had the Rear Chassis Section formed I mark the position of the holes for fixing of the Diff.
Cut some 10mm Plate into two pieces.
Placed the 2 pieces over the mounting holes on the Diff mount.
Placed the Rear Chassis Section in place over the two pieces.
Welded the pieces in place
Drilled four 9.5mm holes in plate
Used an M10x1.5 Tap to put a thread for an M10 bolt
Four M10's which screw in nicely
Finished Rear Section lying upside down on the floor
Rear section installed and Diff bolted in place.