Can a Tomcat who has taken a G: Servant Zondcat drop without it, and if so can they then use Coordinated Orders?
No, they can't drop without it. See the last Effect ballet of G: Servant: G: Servant troopers possessing the Airborne Deployment (AD) Special Skill will be deployed with the same Order their Doctor/Engineer uses to deploy. In such situation, they must be deployed at the same time and on the same table edge segment, or the same Circular Template.
But is the G: Servant ‘attached’ to the Tomcat at list building? I thought G:Synch model’s we’re assigned during Deployment.
"The player must identify which trooper each G: Servant trooper is linked to during deployment. They cannot be used by any other trooper." Which is true. That's for identification purposes to your opponent so it is clear what is assigned to who. What @ijw posted it also correct. The Zondcats are purchased with Tomcats. No other units can take them. You want generic non-AD'ing Servants, then you need a generic zondbot.
Identifying the association to the other player isn’t “assigning” the two models together. In order to legally follow the other two bullet points in that section (and the other bullet points treating the two models as the same for combat purposes) you have to make the association during list construction. The ease by which you can normally fudge the matter, and the lack of decent support in Army, probably just helps mislead people on the matter.
If you had an Tomcat Engineer+Zondcat and a Tomcat (or Dak) Dr (no Zondcat), can you deploy Dr+Zondcat? I see no reason why not. You must identify the association during Deployment, I can't see anything in the rules that says you must associate the Troopers prior to that. It's implied that they're associated; but it's only made explicit during deployment and I see no reason why you can't go against the implicit association.
They belong to the Tomcat, just like a pair of CrazyKoalas belongs to a specific Moran, or Pupniks belong to a specific Chimera, or an HMG belongs to the trooper that you bought with an HMG. For the Daktari to be the one using the Zondcat you'd have to provide a rule letting one trooper use another trooper's weapons/equipment/skills.
oops i thumb up inane post too fast, i thought you were talking of zondbot (which are purchase separately and in my list printed a long time ago i forgot if i build the list with the zondbot attached to the clockmaker or to the daktari). For zondcat, if he belong to the tomcat eng or the tomcat doc is apparent in the cost and value it gives to kill them. Compare Jurisdictional Command of Corregidor ────────────────────────────────────────────────── 2 TOMCAT Engineer Combi Rifle + Light Flamethrower, D-Charges + 1 Zondcat / Pistol, Knife. (0 | 26) ZONDCAT Electric Pulse. (4) TOMCAT Doctor (MediKit) Combi Rifle + Light Flamethrower / Pistol, Knife. (0 | 22) 0 SWC | 48 Points Open in Infinity Army With Jurisdictional Command of Corregidor ────────────────────────────────────────────────── 2 TOMCAT Engineer Combi Rifle + Light Flamethrower, D-Charges / Pistol, Knife. (0 | 22) TOMCAT Doctor (MediKit) Combi Rifle + Light Flamethrower + 1 Zondcat / Pistol, Knife. (0 | 26) ZONDCAT Electric Pulse. (4) 0 SWC | 48 Points Open in Infinity Army