Tourqe converter whine?

Finished my 02 prerunner to 4x4 swap about a month ago. About a week after the swap I started getting a very odd noise. It starts at about 45-50 mph and changes pitch as I get faster. Sounded like a faint electrical whine at first so I disconnected the radio and cb, which was installed at the same time as the swap but the noise didnt go away. Its starting to get louder last week, especially at highway speeds. The transmisson is the only other part I changed so that's got to be the source. From my "research" it sounds like I have an issue with either the torque converter or the front pump. This weekend I'm going to check the bolts holding the torque converter and drop the pan to check the filter and magnets. Anyone know what else could be causing this or some other thing I need to check.