I don't know if you're swapping from an auto or replacing an existing dead T5. If the latter, just get it rebuilt, it'll be much easier. I researched the nuts off T5's before I put mine in but I didn't look at V6 issues.
Your best bet is to ask Mal Wood
https://malwoodauto.com.au/product/tremec-t5-5-speed/That said, I think it will only be a matter of luck. T5's came in a very wide variety of torque ratings, ratios, tail housings, shifter locations, speedo drives and input shaft lengths. They were put in both Falcons and Commodores here.
You could probably be confident that a Falcon one it will fit in the tunnel. A Falcon bell housing won't bolt up to the V6 I don't think, unless they happen to be the same as the Windsor bells (and you get a trans from a V8 Falcon). If the bells are different to Windsor ones I reckon it'll be hard to find one for the V6 in this country.
