To me it looks like the French SOMUA S-35 converted by the Germans to carry the 80mm morter, Am I close
It is SPG and it is not french. Here is more help: Only prototypes were made, and I think this one still can be seen.
It puts me in mnd of a "rounded" hetzer there were a number of replacement projects for that vehicle . It's obviously not the E-10 (the planned hetzer replacement) that AFAIK never got that far in development. On the other hand that upper looks looks cast not welded and the Germans usually didn't do that so not "Panzerwaffe 1946" at all...... there were a number of foreign developments on the Stug concept ..... one guess is the swiss Nahkampfkanone II "Gustav" it has a cast upper hull and AFAIK one sample is somewhere in a museum.
It was tough and I wasn't at all confident of the answer as all I could find was a front picture of the vehicle. What about this one ? View attachment 12558
How old do we have to go Perhaps the Amphibious medium B. Which was an early attempt at an amphibious tank was this modified Medium D, Known as the Medium D**, Wich was used for water trials at Christchurch in 1921. Just a rough guess!
Looks like "rough guesses" are very effective today !!! It is the anphibious medium D that AFAIK sank in the Thames.
Sir that is not a "rough guess" that was in a book written by George Forty who was the curater of the tank museum at bovington tank museum
Can do but I'm running out of interesting pictures. Don't think we had this one before. View attachment 12567
Unlikely you have the book that one coms from, as it's an Italian series published in weekly issues and sold at newstands but the number of surviving pictures of the less common vehicles is limited, not all of them were photographed as much as the Maus.
A few days have passed so The Czechoslovakian, Skoda PA 2 " zelva " ( turtle) Armoured car View attachment 12570