I have a Waltham 21 Jewels,5 position,Size 16 RR watch
Model 16A.I can't find it in the Shugart book.The
movement is shown in the book.Can anyone give me
more information on this watch? Thank You for Your Time

Your watch is a Waltham Grade 1621 which is listed as a 21 jewel movement in the Shugart book. However Shugart listed the watch as being adjusted to 5 Positions, while yours is actually marked "5 Adjustments", which is generally taken to mean temperature, isochronism and three positions.
Being made in the late 1940's you watch would not have met North American railroad requirements at the time it was built. The adjustment to only three (rather than 5) positions and the lack of a micrometer regulator both would have precluded it from being accepted into service under time standards. If you watch is pendant rather than lever set that would be another problem for RR service, as lever setting was also a requirement after about 1908 or so.

Thanks Ed for the information and your time.
Richard