The drum with the blued recess has the hardening I mentioned and does not use the thrust washer.
The one without the bluing is not hardened and uses the washer.

If you plan on using air pressure I would lower it to 30 psi before testing. The rear servo is easier to test if you just install the servo piston then bring it up almost out of the bore then close the apply hole off with your finger tip. Then try to push the piston down. If you can’t the seal is good.

If you used metal seal rings on the front servo piston and retainer it’s pretty difficult to screw those up unless you used a hammer. 😀

Teflon seals should be tested with air like the rear servo using the same pressure rate.

The park rod can easily be placed in the wrong spot. I find it easier to install the rod with the trans vertical, while someone tries to turn the output shaft. The plant actually installed the rod only, then the valve body and they had a tool that held the 3/4 snap ring so it’s could be installed once the rod engaged the valve body.