Back lash noise / end play noise

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My roadster from day one has had this back lash noise/vibration when you come off the load or pull.
No history of Motor from BO.looks to have been reubuilt from appearance.
Haven't done compression .

I bought the 31 roadster couple years ago and the motor was locked up but not sezed loses up easy.
Installed rebuild Zenith and rebuilt dissy . Timed with light. Starts and runs great ,no heat issue.
Oils and water runs clean. A buddy of mine thought maybe it had a alum. Timing gear. Pulled inspection cover but it didn't .We also thought if it didn't have the proper tension spring and plunge in the center of the timing gear it could permit some End play ..

Thought I throw it out there and ask the question before I pull the timing cover to check.

Thanks again , not the first time I've asked for help ....