That can be tricky? G27 (@ 129) was originally Telstar 7, known as T7. But, it had a massive failure a few years back and they switched all 4dtv services to IA13 (@ 121, now known as G23) and Re-Named this bird to T7 in a 4dtv. As far as I know, there are no 4dtv services on G27? But, there are on G23.
Gallaxy 17 is/was a Re-Placement for SBS6 (@ 74), it is currently being re-located and has been re-placed with Horizon2. The 4dtv knew this satellite as B6. As far as I know, there are no 4dtv services on H2?
Hope this helps!