727 grinding at idle

Hey all, feel kind of dumb posting this with no real data to give you, but figure it’s worth a shot. TCI 727, not sure on mileage, drivetrain is borderline “tired”, brand new Hughes torque converter, made this grinding with the old TC too though. Makes a grinding noise sitting at idle in all 3 gears ONCE it’s warmed up. Not super noticeable when it’s cold. Zero grinding noise in park or neutral. Can’t really tell if it grinds while driving due to some loud flowmasters. Shifts fine 1-2, a bit slow to shift 2-3 but have read that’s somewhat normal.

Is there anything I can do or check without pulling the transmission apart? If not I’m going to plan on rebuilding it this winter.