NES question

[NES_Rules]

I bought 2 more NESs at a garage sale and while cleaning both, I realized they were slightly dfferent.  One of them had 8 screws holding the top metal shield on and the other only had 7.  They are both model number NES-001, but the Customer Service stickers are different. 

The 7 screw version has this sticker
[img width=184 height=444]http://i76.photobucket.com/albums/j22/Mike_2_0_0_6/nes001.jpg[/img]

And the 8 screw version has this sticker
[img width=324 height=440]http://i76.photobucket.com/albums/j22/Mike_2_0_0_6/nes.jpg[/img]

All of my other NESs have the same sticker as the 7 screw version, but I didn't look inside to check. 

Is there any reason for this 8 screw version (is it first prodduction run, last production run)?

[captain_nintendo]

Damn my internet at work. I'll have to look at these pics when I get home tonight.

[Tondog]

I'm going to make a guess that the one with the inside Washington State number was made earlier on than the one that only lists the toll-free telephone number.