Per the Long Island Aerospace History website:
“LTA-1 was built as the "Grumman in house test vehicle" and as such was used for Electromagnetic Interference (EMI), electrical subsystems, and form & fit testing.”
At/from:
www.longislandaerospacehistory.com/Select/LM/XXX-LM-PROJE...
Maybe some Grumman/Long Island Aerospace Historical/Archive person will stumble upon this, and hopefully be able to identify some of these good folks…they certainly deserve it.