Armourgeddon claim they have 15 432 30s, some ex Berlin and some they converted themselves with the Rarden modified for paintball use. They felt somewhat top heavy compared to a normal one.
They seem to be in short supply atm, a quick search found some 3/4" ones if you can use them or cut them down to 5/8"?
https://www.scparts.co.uk/sc_en/warehouse/assortments-and-fasteners/hardware-screws-bolts-nuts-washers-studs-etc/countersunk-screw/5-16-unf-with-slotted-head.html
Also used for Upkeep. Contrary to common belief the 8000lb and 12000lb Cookies were a larger diameter than the 4000lb and not just 4000lb units bolted together as can be seen in this photo.
23 Base Workshop was the huge facility at Wetter in Germany. Rather an appropriate name as it was flooded by the bombing of the Mohne dam.
FA was 1967/68 and the VRN site shows 04FA36 as an FV432 mk2 with Rarden turret for Berlin. Your plate reads APC and the 9 in the FV number looks like it has been changed, were the FV439s a conversion from FV432s?