Help dating a pre-'55 Lockheed Test Services belt-back work jacket!

[Fowljesse]

Hi, everyone. I have hit a plateau in my research, and would greatly appreciate help! I just bought a 3/4 length herringbone denim work jacket that has 5 donut hole buttons with "Union Made" on them that are hidden when the jacket is closed. The union tag is very faint, but it is the Duck Goods kind. In the upper left of the tag, it has "A. F. of L.", and has all indications of being pre- 1955. The belt is attached at the back, and has a brass side buckle just above the left pocket hole (access to pants pockets). It has 4 patch pockets in the front, 2 small breast pockets, and hip pockets. On the back, in red chain-stich are the the embroidered words, in an arch "TEST SERVICES". In larger letters, straight across, is "LOCKHEED". Underneath the lettering is the Lockheed logo(Red star, and yellow wing), which are zig-zig stitched on, and detailed red, and yellow denim. Here are some pictures:

https://fbcdn-sphotos-a.akamaihd.ne...719706147_1653698284_2594879_1361294168_n.jpg

https://fbcdn-sphotos-a.akamaihd.ne...729826400_1653698284_2594881_1916306910_n.jpg

Here is a sleeve detail that may help:

https://fbcdn-sphotos-a.akamaihd.ne...7732826475_1653698284_2594883_822942604_n.jpg

Thanks for any insight!
Jesse