GM-295. 1938 experimental model.  It has an almost identical chassis to the HM-275/1941 Model 90, but without the radio.  The "G" is the 1938 model year and the 29 is the number of tubes.  (Information courtesy of Jeff Lendaro)

IHM-171. 1938 5 inch tabletop prototype.   The I could mean "initial".  It is basically a HM-171 but it has an audio channel with speaker and 7 pre-set stations.  GE changed its plans when it learned that RCA was coming out with the TT-5 television attachment.  The speaker was removed,  the tuner was simplified, and the HM-171 was made. Many radios made in 1939 and 40 were advertised as "Ready for Television", meaning they could be connected to sets like the HM-171 and the TT-5 to receive the audio portion of TV. (Information courtesy of Jeff Lendaro)