The plot thickens....
 

Ok, I must be an idiot because I just did the version check at nocalmods and my PS2 has 10 screws, not 8. I guess this means it's V3, not V4. The serial number starts with U1 and the date code is 1A.

I was thrown off because the website I was at before said "if there is an electrical hazard warning on the bottom of the case then it is a V4." Well, mine has the warning, but it also has 10 screws :( I'm assuming this means I can't replace my laser with a KHS-400C?

....damnit.....

EDIT: I did some looking around and if I'm not mistaken, the KHS-400C should work in a V3, shouldn't it?