Long drain for thick sink (drains, bathroom, standard, replace)

[thelopez2]

I have a thick 5" marble sink. I need to replace the drain but am unable to find a standard threaded one long enough. I need a 6" of thread for the retaining nut. Should I buy two drains and connect it with a merchant coupler?

[QIS]

Is this a bathroom sink with an overflow inlet ? If so...does your sink drain have a pop up type stopper? Also,,have you taken the old assembly apart to see how it is configured?