When did it become okay for teams to share technology? The Red Bull and Scuderia Toro Rosso teams apparently share a chassis, didn't that used to be illegal? I remember when it was rumored that the Benetton and Ligier cars shared a chassis and it was considered scandalous.

Also, do the teams all still have to develop their own transmissions, and if so, do Red Bull's and Toro Rosso's have to be different?

It's not legal, but Red Bull has turned it into a "Waffle vs. Square Pancake" argument.

As I recall, when Toyota was working with Williams to mount their engine to the Williams' chassis, they discovered that Williams built a better gearbox and wanted to use it in their car.

I don't think there has ever been a time when the teams had to develop their own tranmissions. X-trac, a third party supplier, has supplied trannys for various teams at various times. Whether a team WANTS to develop its own tranny is, of course, another question.

And Toyota DID use William's gearbox as recently as last year, IIRC.

customer car rules