where is the best place for me to farm this item? How can I tell if laz will 6 socket it?

http://classic.battle.net/diablo2exp/items/elite/polearms.shtml

Larzuk will always give max for high ilvl items.
If you have Giant Thresher 0 soc you will get 6.
Cube gives random.

Note that high level polearms like Giant Thresher only drop in TC85 areas. Further, only normal monsters can drop 'white' or 'grey' items that are used for runewords. Unique and champion monsters always drop magic items. Also having high MF will hurt your chances on getting non-magic items obviously.

Most important part ive learned the hard way searching for whites :P

Remove as much MF gear as you can when hunting