In terms of using other faction's ships with different factions, I know the following works in terms of being tournament legal;

- Rebel Y-Wing = Scum Y-Wing.
- Rebel Z-95 = Scum Z-95.
- Imperial TIE = Sabine's TIE Fighter.

I also know the following does not work;
- TIE Advanced x1 =/= TIE Advanced v1

What about these?
- T-65 <---> T-70.....?
- Imperial TIE <---> TIE F/o.... ?

No, they are different ship types entirely. The two X-Wing kinds are the best example: they've got really different wing shapes.

I'd guess some TOs might fly casually, let you swap, if you contact them before hand and ask nicely. But don't argue if they say no, because that's how the rules are written.

So, no, it isn't legal to swap T-70 and T-65, or TIE/LN and TIE/FO.

A few initial assumptions here:

1. You're talking about Second Edition. In First Edition, of course, you can definitely mix and match ships from the Classic and Sequel Trilogies, but they're definitely different factions in the current edition.
2. You're talking about ship models. Obviously, you can't use Poe Dameron and BB-8 alongside Wedge Antilles in the current edition.

That said... to expand upon what @theBitterFig stated, ship models are explicitly tied to that vessel's model name. That's why Rebel and Scum Y-Wings are interchangeable: They're both called BTL-A4 Y-Wing. X-Wings have variance: a T-65 X-Wing is not the same as a T-70 X-Wing. Likewise, a Customized YT-1300 Freighter is not the same as a Modified YT-1300 Freighter, or a Salvaged YT-1300 Freighter, meaning that all three Millennium Falcon sculpts are unique to their own factions.

Some TOs will be lenient and allow you to substitute models (say, Rebel Falcon v. Resistance Falcon) as long as there is no confusion about what the model represents; but to be safe, it's best to make sure you're using pieces that are specifically correct for their intended usage.

12 hours ago, emeraldbeacon said:

Some TOs will be lenient and allow you to substitute models (say, Rebel Falcon v. Resistance Falcon) as long as there is no confusion about what the model represents; but to be safe, it's best to make sure you're using pieces that are specifically correct for their intended usage.

I agree you should talk to the TO (or your opponent).

One upside of 2.0 - since the TIE/fo and TIE/ln, and T-65 and T-70 no longer share a faction, it should be an easier thing to overlook; if it's a Galactic Empire TIE swarm, for example, that one negative-coloured TIE fighter cannot be a TIE/fo, because the Galactic Empire doesn't use them....