yeah, sorry It's been a while... the ac9 post works best imo with the least amount of modifications, you just have to carve out a bit of the base of the black delrin for the white peice to sit flush... for the did ones your going to have to melt down and dremel out the black insulator, (althought I eventually found it best to completely remove it altogether) then use the dremel to cut a few mils off of the post as its a bit too long.
your best bet, imo... and what i have in my gf's zap and zau, is a solid naval brass post (it has been a while so I cannot remember the thread pitch and size, but all you have to do is find one that matches the top post... although finding real brass, or "naval brass" as opposed to the bronze they sell as brass at mcmaster carr and all the hardware stores, which contains all kinds of nasty stuff including arsenic, is going to be the hard part... just had to put that out there as I dont want somebody getting poisoned and saying it's my fault

)... just cut it to size, dremel out the base of the delrin at the 510 connector to the size of the bolt without the threads, and thread it up though there while heating it... it will tap its own threads b/c of the heat, then just continue to thread it up into the post on top, or take it out and thread it down from there... best option IMO... very little voltage drop under load and extremely easy to clean... I have done the same thing to my zag, SW, and other zen's that I've owned and imo this option lets you really take the best advantage of the superiour construction and quality of these devices while removing their only flaw (in my book)