Donor Car - comparison
Original chassis
Note that the chassis has been reversed: The back rail provides the clearance for the front axle.
The rear part has been turned over to allow an under-slung arrangement; net result, the chassis is 10" lower
The substantial cross-member can be seen clearly, re-riveted in the reverse position.
Note that the same brake cross-shafts have been used, but they attached to a different cross-member (placed further back on the original chassis due to the fitment of a free-wheel unit on the P-Type gearbox. The special gearbox has a Vulcan casing (with large clutch inspection plate).