Thanks very much for the picture, Apophenia.
It's not quite the same as mine, which is slightly from the front quarter, but same side.
Yours has a row of four smoke dischargers (?) at the rear of the turret.
Mine has two, I think, one above the other. It's only a small photo.
Mine also has three grab handles along the turret, instead of one.
Your rear road wheel looks to be a different pattern to the other four. Mine not.
The hatches, fittings on the forward turret top look a bit different too, but its hard to be sure, it may just be canvas covers.
Again hard to be sure, but your front idler wheel looks smaller than the rear drive sprocket, while I think mine is the same size.
Mine is definitely labelled Model 1967. It rather looks as though yours is the first prototype 1964.
My "multifunction" !? scanner still won't talk to my computer, although its printer function is OK.
I realise I didn't post any details.
The ones I have are for the 1964 version, although my picture in the same book is the 1967 one.
20' 4 5/8" x 9' 9 1/4" x 8' 2" high
Ground clearance 16 7/8in ground pressure 9.95psi
4 crew, 52,900lbs loaded.speed 49.7mph on road
Gradient 60%; Vertical obstacle 29.5in; trench 8ft; fording 4' 11"
cruising range 341 (miles I suppose, no units, a bit less than the 372 quoted for the Marder 1)
all units probably converted from metric
Armament a 90mm gun (as in JPZ 4-5 I'm fairly sure) 7.62mm co-axial mg and 7.62mm AA
Daimler-Benz diesel, 500hp.
Did your site say what RU251 means, and does it have a date for the picture?