In this pre-restoration photo, it looks like my RA-103 (console) has the same type of tube as your RA-103 doghouse (i.e., without the bulge at the neck):
My yoke mount has a pair of adjustment slots instead of two pairs of holes:
My mount is pushed nearly all of the way back; I wonder if it could even accommodate the bulge-style CRT.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html