My boat has a pair of sb chevys ,velvet trannys ,and trs drives.
The portside prop turns counter clockwise and the starboard turns clockwise. I have been told that one of my engines runs in reverse rotation but when my engines are running the pulleys look like they are both running the same. does the tranny make the reverse rotation on one side or what?

Not true (like you are seeing). You could have it controlled by either the drives or the transmissions. Friend of mine, his transmissions are the same, and the counter-rotation on one side is actually the TRS drive itself. (also there are some transmissions that are totally reversable buy just altering the shift cable position).

The TRSs reverse the rotation. Although B/W Velvet drives can be set up to run on a reverse rotation motor, they can not be run in reverse at full power. There is a drop center tailstock that will reverse a Velvet Drive, but this is only for flange outputs (IB applications).
Gary