first, volume chapters are not labeled the same as monthly releases.
starting chapters, and the first retail tankubon (commercial volume wise release with bonus etc, that later is translated and resized for our occidental market) messed up the numbering.
volume release numbering is the law, but monthly numbering release is used for ... month by month scanlation basis

.
by checking with the ch-by-ch releases, you will soon get used to this, nothing else to do
and for the actual, available releases, let aside what is on main site download page, we have two running speed-releases of the last 2 chapters (72, 73) hidden in the top 20 recents threads of this forum

but for the olders ones, but still not on the main site download page, all we got is raws (same place, hidden here and there, or available on P2P networks), and scripts, except for phase 71, but i answered to that in the other thread so i let you see
> there <
feel free to help, hey it's as much for you than for us
that's the way it works, community, free scanlation underground sites etc. but the main problem is free time, for all of us
once you have a translated script, even a kid can do a paintbrush Low Quality scanlation (i called them "fastlation" when i do one, occasionaly on mangahelpers

), but HQ, "better than retail commercial release" scanlations, requires even more people than "just" a translator or japanese native people, and a kid.
i am for the casual
"speed LQ release so everyone can have his fix as soon as available, and then HQ volume release because there is bonus stuff and the manga desserves it"- way of life, the way it works in the worldwide scanlation community (except for a chinese team, spamming other teams that dare use their fresh, ultra cleaned, 24hrs-before-first-jap-retail-scan, chinese scanlation of the big shonen series ... but they are an exception)
with the right people, at the right time, it can be a LQ scanlated chapter in two hours, can even be less ! this happens every week for naruto, one piece etc.
of course, but maybe you don't know, Gunnm is no shonen, and the japanese used in it is WAY above shonen one. but for a native japanese who knows english, he reads, he write ...
speed work is sure trash, depending on the scan and quick proofreading, but reading a chapter with the text on, and not in a separate window is nice
while i do buy the books, prefer reading on screen, size is 3x, you can see all details, no food pieces, no need to use both hands or damaging the book ... so HQ, volume releases, is greatly welcomed !

and so i helped teams by the past, and try my best to help this one, but i can't afford the time.
i could have done the help i suggest in the other thread, and not answering to you, so you could have leeched the chapters in few days, but i'm glad i spent the last half hour before going to sleep (it's 4am here) going all pedagogical and stuff, i think it's a better asset.
what's this already, "when you give a man a fish, you feed him for a day, but when you learn him to fish him, you feed him for life" ?
i hope having answered your questions, and that you now know a little better where you are, and how things work

welcole aboard

Experience is the name everyone gives to their mistakes. (Oscar Wilde)
Corporations have no soul to save, and they have no body to incarcerate. (Baron Thurlow)