Delphi is a spin off supplier that was once owned by General Motors. They are now in the market supplying parts to whoever is willing to buy them. Just like GM's old in house axle supplier is now in the open market as AAM and selling to Dodge and Jeep.
ToYo is a partial name of a steering gear supplier. I forget the whole name, I couldn't pronounce it. One of those asian names. Same deal, they are a supplier. Delphi stepped in and offered up a better deal to be the supplier. Could be anything from exchange rates to shipping logistis that played a part in it.
Thankfully they are good steering boxes and I have never needed to open one up.
Just like you want a light bulb, you can get one from GE, or Phillips, or...