A904 Accumulator piston spring.

Years ago I knew a old mopar guy who had more than a dozen of those springs lined up on ledge above his shop door like birds on a wire. To remove it or leave it out at overhaul was the poor mans shift kit for years. If the spring is missing the accumulator doesn't work at all so there isn't a need to block the piston at the top of the cavity. Piston just rests at the bottom.

Interesting information. This transmission was working and shifting real good...very firm, no telling how long the spring had been broken? Car had been sitting since 1988, I drove it for a few months after getting it running circa 2017 before tearing it all down for restoration.
Thanks to everyone for all of the info.