The only Magnum frame NID I have saved pictures of that has cocking indicators is the Chas. Askins/Elmer Keith serial number 500000 --
500000 05.jpg
The pictures I've saved of 31, 32 and 38 don't appear to have indicators.
Serial number 500155 doesn't have indicators and by 500167 that I use to own was a post-1935 Field Grade.