The Russian bloggers have vacuumed up most of the decent images already and they have Russian images of captured howitzers from the 1916 Brusilov
offensive. I like to try to put modern images of survivors on Landships II - sometimes you get lucky like the Russian 8inch howitzers at Warmeriville in France.
Hint - if you use Yandex - try the Russian equivalent of a search phrase it returns quite different results.