Hi all. It's great to be a part of this forum and I'm glad to have signed up.

Anyways, I'm wondering who makes transmissions and transfer cases for all the truck manufacturers out there.

In my understanding, engines are usually designed, prototyped, and built in-house for the most part, with exception to a few examples and perhaps also the new upstart car companies. But for transmissions, transfercases, and differentials, I hear names like Borg-Warner, Dana-Spicer, ZF, and Getrag.

I dont understand why carmakers cant build these components for themselves like they do engines. Perhaps, one of the reasons is that the engine is where the bulk of their acquired technology is dumped into, or where it matters the most...but manufacturers seem to have no problem reverse-engineering each other's products nowadays anyways, so what's the catch?

Thanks for your replies.