The Chief of the Boat (?)

[Mr. Laser Beam]

TOS' jumpsuited enlisted men

AFAIK, any crewmember - officer or enlisted - may wear the jumpsuit, if their duties of the day required it. We've definitely seen Kyle (who is a Lieutenant) wearing one.

 

[Wingsley]

Well, yes, there obviously were cross-overs. It was apparently never a hard rule.

Still, the specialists in the crew seemed to wear jumpsuits and the officers seemed to favor the shirt-and-trouser uniforms.

 

[Captain Robert April]

We've also seen crewmen described as "Technician" and "Specialist" wearing the standard tunic-&-pants ensemble, so who the hell knows at this point...