I'm pretty sure all those were SD. The part in question is a pair of solenoids on the same bracket. Do you know f they're still hooked up? By the way, what ECM are you using? PK, PK1, PC, PE, PF??
if its an 88 Turbo coupe then you are using the wrong code book. A Code 81 is "Boost control circuit failure." Are you still using a Stock BCS? or are you controlling the boost via a Gillis valve. IF you are using the Stock controller.. its bad... if you arent, just ignore it.
Well im sure you could find a listing online somewhere, But my mustang Haynes book has all the codes for SVO's, which are the same codes as a turbocoupe. What other codes you got, i can look em up for you.