[Boatanchors] Mason Labs R-390A?

[W2HX]

Hi all,

I came across a guys about 30 minutes from me who is selling an EAC R-390A radio. I haven't asked what he wants for it but I thought it was interesting. It has some mods by Mason Labs. He said when he bought it (ages ago) the seller told him it was used at NASA. Here are some pix of some of the mods.
https://w2hx.com/?prefix=x/R-390A/Mason%20Labs/

Is this a well-known set of mods or a rarity? Anything about them that improves the R-390A? Or are they just some specialized use case.

73 Eugene W2HX
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