I installed a transmission and now the headlights dont work. They did work before the trans install and now they dont. I am not sure how this even relates to each other, I just think it is a coincidence that they dont work. There is power at the fuse box, but I am lost after that on where to look. Any info would be great.

Did you have starter off?
Some of them power feeds off of starter positive terminal with fuse links there.

Might check Auto Zone web page for wiring diagram on it.