Hi Martin,
There are a few differences.
The mounting brackets for the front bumper is different. Your 72 Moke has the bumper mounting brackets on top of the subframe and the bumper brackets feed through the front grill face plate.
On the late model, the bumper is slung underneath, so doesnt go through the grill.
The upper control arms may have a plate welded on top and a short bump rubber mounted on the subframe tower.
The later wont have the plate welded on and a longer bump rubber.
Not sure about the sump guard nuts welded on for the later subframe.
Other than that, the front subframes would be identical.
On the rear, there is a plate welded on top to strengthen it. Very early models and Mini subframes dont have them.
Cheers
HP