Can someone lead me to the thread or link me to the rule talking about named ship mods.?

IE:

Xwing only mod work for T-65 and T-70

Tie Fighter only mod work for Tie and Tie/FO.

Rules reference page 20: ship type only: this upgrade can only be equipped to a ship of the specified type. If a ship's type includes the entirety of the restricted type it can equip that upgrade.

Any particular upgrade you are wondering about ?

Nah, we was having a discussion in my shop and I remembered something in the forum being kicked around in discussion and forgot how the conversation played out.

Having the page # works for me. Didnt know if it was in the FAQ or rule book.

It might be this thread you are thinking of: https://community.fantasyflightgames.com/topic/194587-youngster-ability-just-for-ties/

It started out as something else and soon derailed into a title discussion.

That would be it.

Thank you Smuggler.