When you swap the trans instead of dealing with the wiring harness and a whole mess of other things....You can just swap the valve body, channel plate, and internal wiring harness from the 04 trans to the 99 built trans that you have.
Don't mind me asking but who built the "built trans"? And also you'll need to verify some of the valve body upgrade in the "built trans" and a few of the main ones are easy to spot like the boost valve. You can swap over most of the valve body upgrades also....all except the ones that require special reaming tools.
