Where does one get an IAC adapter for the TPI throttle body?

I am looking for the IAC adapter for the TPI/LT1 throttle body. (the cast alum plate that bolts to the bottom of the TB that contains the IAC and coolant passage). I ran the P/N from my 86 TPI TB thru GMPartsDirect and appearantly the part has been discontinued. Does anyone sell these new or am I limited to buying used?