web site shows PT 26 at the back, far right of picture. Gene King describes the photo thus:
This photograph shows 77 and 70-foot boats on the same assembly line. PT 23 is in the left foreground, while PT 19 is to the immediate right. In the background, far left, can be seen PT 22, while PT 26 is at the far right; other 70-foot boats can be seen in the background as well. It appears the 70-footers are being gutted for modification prior to their transfer to Royal Navy hands--note the exhaust pipes and other equipment on PT 19's foredeck.
There was a PT 26 which served with the USN, and PTC 26
that was given to the Royal Navy, and which became MTB 316. If all of the boats shown in the photo above are those undergoing conversion ahead of being transferred to the RN, then this would most likely be MTB 316.