904 Transmission - No Numbers??

Hi all,
I bought a 904 lock up transmission a few years ago and I can't seem to identify it or how to effectively identify it (i.e. what car it's from / year made etc.) . I looked in the typical spot on the driver side above the pan and the location where it should be is obvious but no numbers. The picture attached is of another tranny I just got with an engine and this other one looks the exact same, just no numbers.... Any ideas why? Or any other locations that was an alternative marking location?

All I know is:
Small block 904
Lock up (torque converter and machined shaft end)
"Apparently" from an 1985 Diplomat.

Thanks