That is an interesting photo, actually. Taking you chaps as being of standard build and height and also the fact that the gun is on stilts that lift the wheels off the ground by, what, an inch? It is interesting to note how tall the gunshield is. Most models depict the crew huddled, crouched low behind the shield, which I have no objection to at all, it is what we'd all do in a combat situation, but the shield is always represented as only just covering the head of a crouching crewman. I wonder if that is how it would actually be or if said crew would have greater cover, as this photo seems to suggest?
"Right! Open this door or I'll take away every piece of Warhammer you've ever owned!"
Well, it's no PAK 40. The German Pak had the gun sight opening in the angled part of the shield and not in the front part. The muzzle break is "turned" 90 ° compared to the German one.
The height of the PAK 40 was 124,5 cm, so the average gunner had to crouch. The position of the gunner on the sight was not very comfortable, some sitting on the Holm, some kneeling right of it.
Doesn't help a lot because that photo is also wrongly captioned. The Austrian M40 was a recoilless rifle. I think the detailed comment underneath is correct, it's most likely a modified version of the PaK 40 used post war by the Austrian Heer.