The DKN number is just a casting part number and the same on every Major, the number under the seat is however a casting date code which is normally within a month of the tractor being produced.
Yours is April 21 1953 so she is an early Industrial if this is confirmed by other casting numbers on the various parts. Your serial number will be on the flange behind the starter and on a small plate on the fire wall just above the rocker cover. This would help confirming the tractor date.
The workshop manual shows the brakes being cable and rod operated but the parts book shows a rod operation as you say.
I would suspect parts are going to be hard to find if not impossible depending on where you are in the world.
You may also find it helpful to put a question on www.fordsontractorpages.nl.