K5 Serial Numbers?

I might just be thinking of a K5 and ask does anybody know when the old numbers which had the dirty sensor stopped and the new numbers started with the clean sensor? I'd hate to buy one which might be old stock because I'm sure there must still be some around. CHEERS Vic.
P.S. I have the genuine BG4 on my K7 but can anyone advise me on the best of the other copy BG4's CHEERS again Vic.

I'm not sure the serial number helps much.
My replacement K-5 sits firmly in that time and serial number range still but is stain free.

If you buy from a reputable dealer with a good turn-over you are extremely unlikely to end up with one in the sensor stain time range.

Even if you are really really unlucky and get a stained one Pentax and their dealers exchange it without a quibble.

SRS is just a short bike ride down the motorway from you .

Cheers Gwyn. I got my K7 from SRS and if I do get a K5 I will most likly give them my custom again. CHEERS Vic.