Interesting stuff, as I did not know about these aircraft. I'm unclear what the "pressurized equipment" is and where it goes on the aircraft.

Hi Bill. if ive read this correct , the 'Pressurised equipment' 109's , are always the 'odd number G's'.... G1,G3,G5 etc. it means they are meant for high altitude flying , and have sealed and pressurised cockpits (no air-vents, doubled glazed canopys, and a little extra bulge joined to the starboard gun bulge for some other piece of high altitude equipment) ..... like i said , i read this somewhere ,so might be wrong , but im sure some one will correct me if ive got it wrong 😆 hope that helps ya out ☺