another petcock question

hey folks, this is my first post so please give me a little newbie credit on my post . i hope you are not sick of the petcock questions yet. here is my question, where is the best place to get a replacement petcock for a 1982 xs 400 seca, which ones are interchangeable from other bikes to mine? i also have a 1980 xs 650 special, the screw holes are to far apart on the 650 to use on the 400. i have a ttr 250(1980 model) but it is non vacuum. i also have a 1986 700cc intruder non vacuum as well. does the vacuum really matter? i have read that it does not , but some say it does matter. i got this bike from a little crazy kid here in tennessee that Frankensteined the snot out of it. he had put a nobby tire on the back, a dirt bike fuel tank on it no mirrors, side covers etc.,etc. he then rode the crap out of it till it just stopped. i got it on it's last leg and nursed her back to some state of health. after some simple things like correct plugs, getting what used to be oil out of the case, a couple of pod filters,( the air box was gone) a junk yard fuel tank . i now need a petcock that will function properly. my wife is over the amount of time that i have put in on this little girl, (jealous i'm sure) she has a cute little virago that is off limits for part swapping. thanks for your time.....

 

I don't know which ones will interchange with the 400.

There are petcocks on fleabay, but for the price of one of those, there is this:

XS400 tank

If it's rebuildable the kits seem pretty easy to find.

 

Click on the xj forever logo, he has everything you need and is 100% reliable. (little motor pic on top right of your screen)