Tech Questions from current Buyer of 337

[Centered Power]

Thanks for threads I previously saw, but.. actually I referred in my question to the fact that my query is NOT addressed in these threads.

I am not confused about Knots vs mph. I am not asking about the pre 73 vs the post 73 and am not asking about the distinction beween gear extension / retraction vs flying with gear fully extended down and locked ---- these are all quite clear in the various POH's and in the threads herein. -----NO the question --And my apologies if it wasn't apparent is specifically about the difference between 1969 POH and 1971 POH --140mph vs 160mph. All the other verbiage I included was my feeble attempt to show I was already aware of all the matters in the two threads referred to. (Also sme of the confusion addressed in these threads may have been exacerbated by the former change to GAMA "standard" POH.

Back to specific question:

WHY is 1969 POH different from 1971 POH: 140mph vs 160 mph ?

Both of these are pre 73 planes and pre GAMA POH format!

IS there a structural / Parts difference ?

Or was there a recalculation of mechanical stresses by Cessna ?

Or something else?

Thanks again -- also there is question 2 about Robertson above.