I am a Marine vet turned academic historian working with MGRS data from the Vietnam War. I have an overlay georeferenced 1:12500 map of Hue, Vietnam (NIMA Reference L909XHUE) with an imagery basemap. When I use ArcMAP MGRS geocoding, my feature points appear significantly off in the newly created feature layer.
When I use this mapplet to geocode, I get a spot on location. The mapplet appears to use the following datum to successfully plot the grid:
Projection: UTM
Datum: Indian 1975, Thailand
Ellipsoid: Everest (India 1830)
Equatorial Radius (m): 6377266.345
Polar Radius (m): 6356075.413
Eccentricity: .081472981
Flattening: 0.003324449
Datum Transformation (local to WGS84): dX (m) 210, dY (m) 814, dZ (m) 289
