Well, looks like you'll have to go back there! Find out more. I don't recall it on the preserved GN caboose list. For either ND, or MT. Hmmmm.... Boxcab E50
No idea... Without my Hickcox book handy (GN Color Guide to F/P Equip), I have no caboose data available.
The Hickcox book has no data on any X700-X724 series cabooses that lost their cupolas. Must have been a BN-era modification, or by the current owner.
There was, may still be, a GN caboose in the museum at Snoqualmie, WA. It also had a removed cupola. I do not recall a story behind how that happened. Might have some info around here. But am not up to tearing the house apart, to locate which box... Boxcab E50
Actually, I ended up looking for some other paperwork much of the day... No. I did not find that either. Boxcab E50