This Marshall with the aluminum chassis has the Radiospares "De-luxe" power transformer and it would seem one of the first 8ohm, 16 ohm & 100v line Drake output transformers. It may have had the shared cathode at valve/tube 1 with the 820 ohm resistor and the 320uf capacitor to ground.
It did originally have very "skinny" red 5 watt screen grid resistors for the KT66's which it came with. I moved the handle on the top of the cabinet to straddle the balance point as it was very heavy at one end and hard to carry.
It used the perforated circuit board and has no "mounted can" electrolytic capacitors on the top side of the chassis. I bought it used in about 1972 in London - s/n 6696.
The Marshall Logo was missing and at the time the only one in stock at Rose Morris was the large one.-Peter H