Hi,
My 96 3.0L Auto with Aircon uses the 93181720 and i would have thought that this should be the one for yours as well :-?.
I got the info. below from my EPC which doesn't even mention belt # 93181720 but instead 93181721 which I've highlighted:-?.
1 BELT,DRIVE,21.36 X 1900 MM,ALTERNATOR (IDENT FK) (NLS.- USE 9118618 OPEL 91126386VAUXHALL)
EXCEPT AIR CONDITIONING X25XE,X30X 1 90409782 13 40 742
2 BELT,DRIVE,21.36 X 1900 MM,ALTERNATOR (IDENT FW) (NLS.- USE 9118618 OPEL 91126386VAUXHALL)
EXCEPT AIR CONDITIONING X25XE,X30X -W1193599
1 90500228 13 40 614
4 BELT,DRIVE,21.36 X 1900 MM,ALTERNATOR (IDENT FX) (FOR DELETION OF AIR CONDITIONING PARTS) (FOR VAUXHALL) (NLS.- USE 93181719) X25XE,X30X W1193600-
1 91126386
7 BELT,DRIVE,21.36 X 2260 MM,ALTERNATOR (FOR JAPAN) (IDENT FX) (NLS.- USE 9118620) (SEE SERVICE INSTRUCTIONS)
USED WITH AIR CONDITIONING X25XE,X30X R1000001-S1059678
1 90500354 13 40 615
6 BELT,DRIVE,21.36 X 2020 MM,ALTERNATOR (IDENT AC) (USED WITH AIR CONDITIONING) (NLS.- USE 9118620) (EXCEPT VAUXHALL) X25XE,X30X S1059679-X1032987
1 90528761 18 54 728
6 BELT,DRIVE,21.36 X 2020 MM,ALTERNATOR (IDENT AC) (USED WITH AIR CONDITIONING) (NLS.- USE 91126388) (FOR VAUXHALL) X25XE,X30X S1059679-X1032987
1 90528761 18 54 728
9 BELT,DRIVE,21.36 X 2020 MM,ALTERNATOR (IDENT FX) (USED WITH AIR CONDITIONING) (FOR VAUXHALL) (NLS.-
USE 93181721) X25XE,Y26SE,X30XE,Y32S X1032988-
1 91126388
10 ROLLER,TENSION (NLS.- USE 90528760) X25XE,X30X 1 90409783 13 40 536
10 ROLLER,TENSION (NLS.- USE 9202550) X25XE,Y26SE,X30XE,Y32S 1 90528760 13 40 547
10 ROLLER,TENSION X25XE,Y26SE,X30XE,Y32S 1 9202550 63 40 538
11 -PULLEY,TENSIONER X25XE,Y26SE,X30XE,Y32S 1 9157962 13 40 512
12 -SCREW,PULLEY,M10 X 30 X25XE,Y26SE,X30XE,Y32S 1 9157950 13 40 801
13 -NUT,PULLEY,M10 (NLS.- USE 12992580) X25XE,Y26SE,X30XE,Y32S 1 9157951 13 40 802
13 -NUT,PULLEY,M10 X25XE,Y26SE,X30XE,Y32S 1 12992580 13 40 832
14 -COVER,PROTECTION,TENSIONER X25XE,Y26SE,X30XE,Y32S 1 9157963 13 41 667
HTH,
Pete

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PS. It seems to me that both the belts that dbug has mentioned have had the last digit added to by 1 in the EPC that I've shown, Very odd :-?.