If it was the KDY insignia, what was it doing on the helmets of some of the clonetroopers? Is KDY in league with the oh-so-secretive Kaminoans?
Sienar. Builds only smaller ships (like Darth Maul's) and currently works on the Twin Ion Engine *geekish TIE-Fighter sound from this side of the screen*
Incom. Currently producing the Z-95 Headhunter and they never did bigger ships.
Calamari never produced ships for anyone but themselves.
Correllia Engineering Corp. They build freighters and cargo ships only. Not really suited for troop transport.
The Trade Federation. Well, they wouldn't like to build ships for the republic and the republic wouldn't like to pay THEM for the ships.
Noobian... Well, Naboo is a peaceful planet... blah, blah, blah... *Deathstar Testing: POSITIVE*
Kuat Drive Yards. Well, they are big, nasty and corrupt. BINGO!
To answer the helmet question:
Kuat does produce space suits and military equipment.
The clone trooper/stormtrooper suit has limited zero-g capabilities.