Vibration at 2200-2500 RPMs
I am having a new issue (or if it isn't new, it wasn't as noticeable previously) where I am getting a fair vibration with the engine turning at about 2200-2500 RPMs, regardless of whether or not I am moving. I have not noticed anything outside of this range, either lower or higher RPMs. I can be driving or sitting with the clutch depressed and revving the engine and the vibration will still occur. I have had the engine replaced (with another I6 4.0L, approx same mileage-50k) approximately one year ago due to excessive water in it and, at the same time, I had the clutch changed. I had to bring it back shortly after since the throwout bearing was ticking and the throwout bearing was changed again. I have not performed any other maintenance on the engine except for the routine oil changes and have only put approximately 6-7k on the engine since.
I have done searches and many seem to point in the direction of the torque convertor (bolt being loose) or a motor mount. However, I didn't think that a manual transmission has a torque convertor. Are there any other ideas of things that I could look for which could be causing this?