John, you are absolutely correct!
Never heard of D5's, unless you mean 05D (Radio Direction Finders). Similarly, 05H is Morse Intercept Operator, if that's what you mean. It must have been shop talk where you were at; I worked with the above two designations and others and never heard them called by those handles!
My dyslexia is coming through...I guess. Yes under the MOS system they were 05H and 05D, yet mine did not fall into those catagories specifically. Since we were of the
"4 R's" (No Rank, No Recognition, No Respect, and No Record), most were cross specialized. The closest I get to a modern MOS is probably a 98C...hard to configure as I was recruited right out of ROTC in '72, but never commissioned(would have been if I re-upped Regular Army in '75 as they were dismantling the ASA). Had duty stations in Berlin, Hong Kong, Laos, Cambodia(these last two we will not go there), and Finland of all places. My primary duty was direct information gathering, deciphering, and translating perception into intent. The largst group I worked in was in Hong Kong that consisted of eleven of us with no designated "officer", just team chief. In Berlin I had a designated 05D and 05H(no longer just high speed telegraph, but radio reception enhancer too), and me. In Finland we had six of us working out of Ivalo and then Kotka...Ivalo is colder than Siberia!