HAHAHAHAHAHA, yeah...we were shooting in the dark a bit.
Took me awhile, but I found one for ya. Option has them for $55...seems like a bit much
http://www.optionimports.com/gtcoouad.html
I googled compressor outlet adapter, then GT28 outlet adapter...ended up being the better search. Is this what you need?
WD
EDIT
FRSport has them for $39 I am the coolest moderator on the ENTIRE internet
http://www.frsport.com/Turbo-A....html