WT1,
The first 3 of the 2c Navajo stamps (1 from 2004 and 2 from 2006)had different Scott #s originally.
But then they did some renumbering...
No. 3749 becomes No. 3750
No. 3749A becomes No. 3751
No. 3749B becomes No. 3752
and then the 2007 version came out and it got Scott # 3753.
Here's the easy way to tell what's what:
3750- 2004 year date - no micro print
3751- 2006 year date-large date, no micro print
3752- 2006 year date- small date, with micro print on the right
3753- 2007 year date - with micro print on the left
And here's a pic showing the two 2006 dates - you can see the first one in the pic is just a little bigger than the other one. I also circled the areas where the "USPS" micro print is located.
Hope this helps.

Oh, and there is a year 2011 2c Navajo stamp too. It is Scott # 3758B and has water activated gum, but I don't have one of these yet, so no pic.
Dave N.
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