The first image doesn't make any sense to me
It certainly looks like it is lacking a turret and therefore I am lead to suspect it's an SU variant, in this case either an SU-85 or an SU-100. However, upon closer inspection, I can't see either vehicle in that image.
First off, the very front of the hull, where the bow and glacis plates meet, is rounded and not angled, which immediately rules out the SU-100. Also, for an SU-85 the gun should be positioned lower in the hull and to the right of the driver's hatch (as seen from the driver's point of view). Then there's the hatch, or what I presume is a hatch, on top of the superstructure. For an SU-85 it should be on the left hand side of the superstructure, here it looks like it's on the opposite side. Strangely, the more I look at the image (and I think I have stared myself cross-eyed by now
), the more it looks like the gun simply doesn't seem to fit the vehicle! It actually looks like it belongs to something in the background of the image.
I have to throw in the towel on this one. I am stumped!
On to the second image. Once again this is not an easy one and I must admit I am not quite sure...
It looks like we are again dealing with a turretless vehicle. There is what looks to be a gun silhouetted against the sky poking out to the right of the vehicle. It seems to be quite short and therefore should not belong to an SU-85 or SU-100. Nor is it an SU-122 w/ M30 howitzer. This weapon has a very thick sleeve running up half its length and I can't see that here.
This leaves the SU-122 w/ U-11 or D-6 howitzer. The weapon on this vehicle also has a short barrel but it is without that conspicuous sleeve. The same weapon was also mounted on an SU-100 chassis and designated SU-122M. However, the SU-100 chassis has a protruding bulge on the right hand side of the superstructure in order to accommodate the commanders cupola. Though the image makes it difficult to be certain, this commanders bulge seems to be absent.
If it is an assault gun, then I would have to go with the SU-122 w/ U-11 or D-6 howitzer.
There is one more possibility... Once again on the second image, I think the gun looks suspect. I therefore feel obliged to consider whether it might be an T-34 ARV. The Germans did capture such vehicles and re-equip them with 3x20mm cannons, such as those on the SdKfz 251/21 w/ 20mm drilling. I wonder if the short barrel on right could be a 20mm cannon?
In short, it's either an SU-122 w/ U-11 or D-6 howitzer or a T-34 ARV w/ German 20mm drilling.
To be honest though, these remain educated guesses and I very much look forward to finding out what the answer is