You're not supposed to find them... ONLY I CAN FIND THEM...
Seriously, you can spot transitionals by:
Looking at the serial number located on the bottom of the butt: It will have a letter "S" prefix, but the letter may not be located close to the number. As a rule the number will be at or under S-990184, but I have seen exceptions with higher numbers in the S-900,000 series. The series started at S-811,120 in Sept. 12, 1945.
The hammer spur will have fine checkering. Later "short-action" revolvers had hammers with course checkering, and are numbered above S-990185.
Almost all were blue finished, but some were factory nickel plated. Barrel lengths of 2", 4", 5" and 6" are found, with the 2" and 6" being more scarce.
They are all 5-screw variants (4 sideplate screws with one possibly covered by the stocks, and a screw in the front of the trigger guard) and have pinned barrels with half-moon front sights that are 1/10" thick.