Signal Corps unit DI; ID and era?

[cwnorma]

DI's are outside of my wheelhouse and a freind recently asked me if I could Identify the unit and era of this DI:

 

Your help is greatly appreciated.

 

Chris

[BILL THE PATCH]

Signal Corp school, but mine is a yellow backround, post war probably 50's era

 

Sent from my Moto G (5) Plus using Tapatalk

 

[tredhed2]

Three-digit manufacturers codes started in the 60s.

[cwnorma]

Thanks! So the background is supposed to be Yellow? Is this a manufacturer's error or just a variation?

[tredhed2]

Orange and white are SC colors. The yellow is a variant. This design is approved and sample approved and manufacture by Green is authorized.

[patches]

And with a hallmark like that will date from 1964-65 tll 1974, afterwards Made in USA is added, added by all makers.

 

[BILL THE PATCH]

Here's mine which is yellow background, but no Hallmark, when would this date to?

[tredhed2]

Done by a jobber, quality not too great, wrong color too 1940s-50s

[cwnorma]

Thanks for the ID!