Actually the one on the left was for 70-74 MY & the right is the 75-76 + Superceded for all 70-76, with the ribs added to stop the engine heat warping of the tray of the early ones, which then allowed a waterfall over the front edged L & R between the mounting screws in medium to heavy rain.
Both will mount for all 70-76 MYs, & if you went to a Porsche dealer in the late-70s - 80s/90s - that's what they'd sell you as a "superceded" & improved version.
Both types have been NLA from Porsche for some time now, but repros of both types are out there.
If yours is a Daily Driver or Weekender 914, &/or only doing local & Porsche Club shows where originality is not judged (check your local clubs' & shows' rules), then it's okay to use the right later one, & you'll be better off for no heat warping.
It's your choice, but you can definitely use the new right one.
If you want exact originality - then look at Mikey914 for the upcoming group buy on his repro early tray from 914Rubber. It's got a topic in both the Garage & Parts or Member Vendor forums. You can also PM him to get added to the GB.
Cheers!
Tom
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