US units don't have date codes. However, yours is listed as August 2010 which should be downgradable. You can download the min version PUP from PSX scene to see the min FW version you can downgrade to. If it's 3.55 or lower, you're good to go downgrading.
There's a couple threads I linked in a couple threads down, however if you're not familiar with soldering or have an E3 flasher on-hand, I suggest you find someone locally to do it for you.