I would say a SiG 33 gun on a Pz III chassis so .. Sturminfanteriegeschütz 33B BTW here's the full pic http://www.wwiivehicles.com/germany/self-propelled/sig-33.asp
only thing more that i have to add is that objekt 237 was the other of the two initial kv-85 prototypes but the photo is labelled either way on many sites. battlefield.ru give it as a kv-85
It is a KV-85 prototype, the gun is visibly much longer than an F-34, my source reports it as the S-31 but it could be the non functional S-18. I have it as Objekt 238 but your 237 as may be good. What I was looking for was KV-85 prototype and Objekt. According to Zaloga the turret ring in prototypes was too small for the 85 and the production KV-85 had a Stalin turret with a wider ring. Your go. EDIT: Wiky reports the KV-1 as Objekt 239 and the IS1-85 was the Objekt 237, some confusion here obviously exists.
I read about approximately the same concerning the guns and turret S-18 'looks' more likely for the one in the photo. There's a lot of conflicting info online. Perhaps the JS hulls trialled are the reason for the confusion. There was some discussion on a modelling forum that the reports of a team from the west that examined them after the war are responsible for the conflicting reports. The Soviets have apparently always called them just KV-85 prototypes. Couldn't find any actual original reports, but my Russian is not up to searching for that with any real chance of success. Maybe worth a thread later - not sure it's so much of an issue. Anyway, how about this one;
The pics look very much like the tank at Kublinka, they both have the KV1-S mantlet, has anyone details on that one? And for your post is obviously a refugee from the "tankette" thread with a possible Carden Loyd ancestry, but that's as far as I go.