Nothing. Are you sure, here isn`t the typo? If you look at google, PN43D490 is real TV model, but if you look for PL model, you`ll find nothing serious.
PN is more realistic because Samsung uses such acronyms (PN/UN/LN for USA tv models).
I just made a new topic asking a question about this model but listed as PN43D490 but it was deleted without reason? I was just wondering if the SamyGo Extentions for MSTAR T-MST5DEUC were going to be or could be modified for T-MST4AUSC, or a strat on how i could do this myself.