340 with old Harland S rockers geometry?

I got to compare the 1.5 to the 1.6 rockers today after work. Took some pictures.
Just can't seem to find any difference. The rocker on the left or top in all the pictures is the 1.5
The dimples look to be in the same location on both rockers.
The part number on the rockers are the same... SPE16.... however one of the rockers is stamped 1.5....?????
Seems to me the 1.5 should have a part number of SPE15... wouldn't you think?

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