I don't think this volume exists, or I've never seen or heard about it.
About No. 2 Squadron, there's no list of serials and letters in Hans Onderwater's "second to none".
There's no tie-up with letters in "aircraft for the many" either. From that second book, FR919 served with No. 2 Squadron from 4th May to 28th November 1944. The author also stresses the point that No. 2 and No. 268 Squadrons were drawing aircraft from a 'pool' in Gatwick.
As for No. 168 Squadron, Phil Listemann, who also frequents this board, had published a small book about his unit :
top row, first from right.
In the list of aircraft lost by the Squadron, you can work out a few Mustangs, as Phil added their postings before 168. I can add FD445, which was lost in my area, near Cambrai, on 3rd January 1944, issued to 168 on 23 June 1943. I wish I could find the individual letter of that Mustang.
He tried to match serials and letters, but it proved elusive for that Squadron.