Marlene's auto -> manual swap has logged about 1000 miles and, since day one with the manual, she's had a bad vibration in both third and fourth gears.

Here's the facts:

1)This vibration manifests isself in the 1400 to 1900 rpm range and only in 3rd and 4th gear.

2)The vibration only occurs when the the drivetrain is under load either accelerating or decelerating. If you feather the throttle to minimize/nullify the driveline load, the vibration goes away.

3)The vibration is (I'm guessing here) about 30-50Hz and doesn't seem to increase in frequency. If it does increase, it is only a slight change. The amplitude is significant; if you really have your foot in the throttle, it will blur the image in the rearview mirrors.

4)Driveline and engine support status:
— All new motor mounts (front and rear)
— Remanufactured driveshaft installed 10/03 (did not vibrate prior to tranny swap)
— Stub end of driveshaft shortened during swap using piece from donor car. End bushing has been checked for fit on the transmission output shaft and feels the same as the reman stub.
— Driveshaft was balanced when shortened. Has been separated a couple of times but has witness marks and has been reassembled correctly.
— Overall, I'd say the transmission is quiet. No apparent chipped-tooth sounds, no whining. The fluid was replaced during the installation.

I guess what I'm looking for here is other's experiences with the four-speed manual. Particularly failure modes and bad gear box experiences.

Danke schöen!

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Never a dull moment at Berry Hill Farm.