Good news...I found the photo, bad news...the artwork based on it in Osprey's Anzio 1944 is wrong. The Panther A in question actually does have Zimmerit in the photo. This is not as easy as I first thought. I did manage to find the combat history of the 1/ PzRg 4 in the Combat History of sPzAbt 507 , as they were attached to the 507th during the campaign, then absorbed into the 26th Pz Dv. Here again, grainy photos make identification difficult. On page 188 of Combat History of sPzAbt 507 there is a photo which could go either way, sorry I don't have a scanner or I would post it. The photo you posted of 221 appears to have Zimmerit. Starting on page 42 of this; http://www.scribd.com/doc/82564016/Panzers-in-Italy-1943-1945-English you will find photos of 1/PzRg 4 Panthers. 221 is finished in overall Dark Yellow with crosses at the far front of the hull sides and between the exhausts on the rear. No crosses on the turret. At least some had turret numbers on the turret rear as well. Osprey's Modelling the Panther Tank covers a detailed built of Panther 415 of 1/PzRg4, but alas, with Zim.
The only photo of a Panther A without Zim that I know of of the top of my head is on page 62 of Jentz's Panther Tank, the Quest for Combat Supremacy and it certainly isn't in Italy. You only have about a week's worth of production from the 4 plants before the introduction of Zimmerit, so finding a photo will be difficult at best.
Here is a shot of the rear of 221;
http://forum.axishistory.com/download/file.php?id=250556&mode=view
Note the storage box and bundle of fascines on the rear deck, as can also be seen in the side view of 221 you posted. You can also see the small square-patterned Zimmerit clearly on the left rear hull storage bin.