Special Delivery With Plate Number

I gather plate number singles and put hem aside for eventual sale on ebay. I was staging some today for photos and ran across this one; I haven't seen many with this much of the plate number on the stamp itself.
don

E15....slight misperf.

Here's an interesting ebay listing on a similar E15, but with an entire plate block:

http://www.ebay.com/itm/U-S-E15-PB-...190608700205

Note the comment that LR position plate number 19280 35 is said to have a known "cracked plate". Actually, my Scott Specialized Catalog references it as E15b "gashed plate". I don't think either the stamp scanned above or the ebay listing show that particular variety.

As this is not my area of study, can anyone confirm that since the stamp shown is plate number 19280, does that automatically make it a E15b (gray lilac) variety as compared to an E15 (gray violet) or E15a (red lilac)?

According to DURLAND....
#E15 plate #19280...cv for PB $5....common plate #

35.....listed is the position.
1 2 3 4 5
6 7 8 9 10
......35
It is not in the PB format but from that sheet.
PB 19280 LR would be position
44 45
49 50

Gashed plate is more accurate, it is in the E of the word cents. I saw one about two weeks ago.