Who has shipped a transmission?

Buy a bin from walmart that the trans fits in.

Line the bottom with some cardboard.

Put trans in.

Stuff cardboard around it and on top of it.

Put lid on.

Cut slits in lid and ziptie lid to the bin.

Arrange for it to be picked up at your doorstep via DHL.

Charge 50% more for shipping than you paid. Profit.