Here is he German SiG 33 SPG. It was a SiG 33 feild gun mounted on the chasis of a Panzer I light tank. The vehicle was overloaded and often the suspension broke. Speed was slow, and the huge gun sheild made an easy target. Now before someone says the sheild is too tall, it isn't, I checked the height of the vehicle and made sure my image was of the same size (may be off a pixel or two due to rounding decimals). The whole vehicle was about 4.7m high with only 13mm of armor.
Something seemed funny about it to me, but after an hour of trying to find out what and making slight coloring and shading changes, I just posted it.