Made by the brilliant creator of the CoH2 realism mod, Trapper(MM).
And just to clarify, no the pictures are not photoshopped or edited or altered in any way.
The Sherman Jumbo and many others are available in Trapper's CoH2 Realism mod (https://steamcommunity.com/sharedfiles/filedetails/?id=904421369) so you can try it out.
He explained to me that a custom skin was used to "cut" the barrel of the 76mm Sherman.
Similarly one could create other units by "cutting" features from the in-game models via custom skins.
Sadly skins cannot add things to the model of the vehicle, for example making the barrel of the M10 longer to make it the 17 pounder version.
Just want to share this with the community as a last effort for a Jumbo for the USF Urban Assault Company in the place of the bulldozer.