Louisville Slugger Dates/Era

[BaseballGM]

I've been looking online for clues to determining the dates or era LS bats were used. Are there exceptions to these guides? Did the 69-72 bats always have the P loop crossing the stem? What dates would you put these as?

[CampWest]

If I'm not mistaken, the Powerized on left was used 1970-72 and on right was used 1964-72.

[CampWest]

I'll add, I think the bat on the right has a 1964-69 center brand, making it a pre-1970 bat, whereas the bat on left was probably 70-72.

this is one of the better online resources
http://webpages.charter.net/birdbats/Birdbats/Bat%20ID/LS%201950-1979.htm

But this is a great resource to have on hand... Vince Malta's "A Complete Reference Guide Louisville Slugger Professional Player Bats"
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&hash=item20c135e3d3&item=140680487891&nma=true&pt=LH_DefaultDomain_0&rt=nc&si=NvlImX3whJ%252FUlGVCTujYx%252FXGRDU%253D&orig_cvip=true&rt=nc

[BaseballGM]

Thanks for the response and info. Any other opinions are welcomed.