where do i get a new front diff.

    I'm not going the junk yard route on something like this. So what companies sell these things. Or who has good instructions on rebuilding one (Haynes or Chilton). 

try calling these guys i heard great stuff about them they even do custom third members if your interested here's the link to there website
http://www.differentials.com/index.html

http://cgi.ebay.com/ebaymotors/4WD-FRONT-END-CHEVY-BLAZER-JIMMY-TRUCK-SONOMA-S-10-S10_W0QQcmdZViewItemQQcategoryZ33731QQihZ011QQitemZ320139104379

only $250

If you don't want to go used or the JY route... You're most likely either stuck going to the dealership, or something like thegr81 posted...
 
You could use this as an excuse to upgrade to a locker or something up front, lol