Look in civPack in modmod section.
@Thunderbrd
Is it by purpose that my vassal refuses to give me a tech as a tribute?
Vassals refusing to hand over tech for free is a holdover from vanilla Civ 4, C2C didn't change anything on that front
Yeah, currently vassals are only good for self-imposed quests like vassalize-em-all (literal application) or get-all-cultures (and demand them from eager vassals).
I don't see any other REAL benefits of having any vassals, lol - and I see a ton of problems with being stuck with some of them that are useless.
Or at best, it's still useless.
Vassals are also good for supplementing your research, assuming they're in the same era as you and produce a non-trivial amount of beakers (e.g. your vassal can research Marine Biology for you while you research Civil Engineering)