Boarder:
I'm surprised that you're using 6600 for this, it will make things more difficult because it's such an early vehicle.
On the rear wall, you'll need to remove the antenna base stub at top right, and the 4 tiny clips for the toolbox at top left. But worse, the two poles for holding the adapter are at the wrong angle. They should be at 60 degrees:
AS for the toolbox at the lower left, it was missing in the Bundesarchiv photos, so you'd only need to build the frame that held it. I can post diagrams if you need.
The correct turret bin is the standard one, you can get it from a Late Tiger etc.
In the photos, the rear mudguards of S33 are missing, so there's no problem there. The front ones are the standard ones with a hinged side portion; don't know where you'll get them!
The crane holes at the front should have the reinforcing rings.
You're using side panels from a Late kit if I read you correctly? The track cable on the left side will have the wrong layout, so even the clips will need replacing.
S33 didn't have the two small holes above the driver's visor.
S33 had at least the clips for a full set of tools on the hull roof; you won't find them in 6600. That includes the large shovel on the glacis plate.
The holders for the tow cables were different; closer together. There were 6 portions in the cleaning rod, not 5, and they were shorter.
The front edges of the lower hull were different, and the tow shackles were slightly moved.
The S-mine launchers were partly missing or damaged; I can post diagrams of their construction if needed.
There was a shaft stored on the bottom of the rear wall; that's not in 6600.
S33 had the loader's periscope on the turret roof; is that in 6600 at all? It also had track holders on the turret sides, albeit with some damage.
And it must have had the triangle on the rear engine compartment cover, another difference from 6600.
All in all it's a lot of detail change. I just know that Dragon will release two or three kits to cover this time period.
David