Took the car to get it aligned; they pointed out that first I needed to get the passenger inner tie rod ball joint replaced - the boot was torn and the joint had a decent amount of play. They wanted too much to fix just that joint; I ordered the parts to replace all four joints and both boots for less, but won't be able to get it all installed until next week at the earliest.

Further, I've just checked the motor mounts visually; they LOOK fine per what the manual says. Then, I put the parking brake on and the hood up; looking under the slot at the base of the hood from the driver's seat and started the engine.

Slipping the clutch in forward or reverse, even pretty abruptly, I couldn't get the engine to move or jerk relative to the body.

I didn't jack up the engine a bit to wiggle the mounts as instructed - anyone a big proponent of that?

The reason I started to suspect motor mounts is that as I shift through the gears, there's a definite "klunk" as I disengage and re-engage the clutch.

 

Get the suspension stuff taken car of and see if the noise is still there.....if there is free play in the suspension, as you shift gears you are removing the torque off the wheels, the free play can allow them to "shift" causing a clunk.