Hey gang, just a little FYI: the TT-4 KSRs were around at least as early as 1954. We had 'em in our then-new AN/GRC-26D HF radio/ratt shelters then, when I was an instructor at The Signal School, Ft. Monmouth, NJ. That would be -umm- 10 years before our Viet Nam involvement-in-force began. Ed Greeley