I am looking to purchase some drive showers for my TRS drives. Any opinions on which work the best and fit the best for TRS drives.

Not really a big need for a shower on the TRS, it's got an oil pump. They run a lot cooler than a Bravo.

I was told rex marine had them but they e-mailed me back saying they were out and not sure if they were going to get them anymore cause of low demand.

I have also been told that they are not needed. I do know a few guys that put water dumps centered over the drives to keep them cooler.

I had made a set for ours , its really not all that hard. then we took them off and just made a cap to go over the top of the drive and supply water from the engine , from the bypass valve on the cool water side. Remember the drives have to get some heat to flow the fluid at high enough rate that it won't cavatate the fluid. Be sure to run synthetic fluid to.