You are right sir... I forgot to mention those, since they are not spec's.. They are Japanese market only rack mountable separates. The C73 pictured there is indeed the same as the SPEC3 western substitute, The M73 has no western substitute.
The comparison is like this:
C-73 --> Spec 3
C-77 --> Spec 1
M-73 --> no substitue
M-75 --> Spec 4 (there is a little difference here, being the knobs between the VU's)
M-77 --> Spec 2
Interestingly enough there is also a separate rack mountable tuner, being the F-73, which is about the same as a TX-9500.. Furthermore there is the CT-97 rack mountable cassettedeck, which is technically the same as a CT-F9191..
There are some more rack mountable separates as well for the Japanese market, but they are from a different quality and specs with them. Being the: C-1500, SC-1500II, SC-1800II, M-1500, SM-1500II, SM-1800II and the F-1500.
Cheers,
JW