Transmission side-side clunk in neutral (out of car)

[wss4]

This is probably a long shot from a troubleshooting perspective, but I've got a transmission out of a wrecked car that I am planning to put in my car soon to replace the worn existing transmission. The new(er) transmission makes a fairly loud clunk when left in neutral and rocked side to side (no noise when rocked front to back). It is definitely something shifting from left to right, as I get the noise even when rocking the transmission very slowly. In any gear, the noise is much less loud. The clunk is coming from the top rear end of the transmission near the gear selection shaft (seems to be centered about 5-6 inches forward of where the gear selection shaft exits the housing, and on the passenger side). I can get into all the gears ok.

Does anyone know if this is normal for these ZF transmissions? I would hate to install a damaged transmission.

[wss4]

FYI for anyone who might have this question in the future - it is normal. Sounds like it is a dowel/pin that slides left/right around the 1/2 shift gate assembly

[XMetal]

Thanks for posting a follow up on what you've found