will a vw lupo gearbox be okay to go in a polo?
If no one replies it’s because neither of those cars are sold in the United States and this board is based in the U.S.
In addition to what Dave said, I would add that you might be more likely to get a useful response if you add the missing details:
Engine type and displacement of the Lupo and the Polo
Model year of both cars
4 speed or 5 speed transmission
The US-equivalent model names for both the Lupo and the Polo
While VW markets cars in the US, there tend to be many detail differences between the European-spec models and the US-spec models, including engine sizes.
I suspect you’re in Europe somewhere (probably UK) since niether the Lupo or Polo are sold in the US.
Polo and Lupo share the same platform as do several Seat and Skoda models, ‘some’ transmissions are interchangeable. Your best bet is to take this to one of the many European VW specialist forums but make sure you give the years, engines and transmission types.
There is no U.S.-equivalent here because Volkswagen doesn’t sell cars that small in the United States.