50kHz radios
All current GA nav radios support 50kHz spacing (therfore 40 channel glideslope). A few very old (Narco 12A with UGR2 glideslope Rx's ?) units may still be around, but all Garmin and Honeywell and Narco equipment produced is the last 20 years or more is certainly compliant.
Regards
Wigglyamp