Confused about PS3 model @_@

Hi

I spent many hours hunting a used PS3 that has FW lower than 3.55 but I think I have to give up now.

Anyway, I think I will give another chance hunting a brand new one with FW 3.4 or 3.5 but looking up on http://www.ps3devwiki.com/index.php?...#Retail_Models makes me confused @_@

The confusing part is, as you can see on the chart, the one to avoid is the "CECH-30..A, CECH-30..A(current model), CECH-250.A and CECH-250.B" because it comes with FW 3.61 and above and therefore cannot be downgraded.

BUT!

If you scroll up a bit, the model that comes with FW 3.50 also has the same model number as the one that comes with FW 3.61 which are CECH-250.A and CECH-250.B!!

Now if I pick up a box and see "CECH-250.A or CECH-250.B" how would I know for sure that it will be FW 3.50 and not the 3.61??

In other word, when I pick a brand new box, what is the magic model number that I should look for?

Note: I live in Australia so it will be PAL model.

Thank in advance