Or, if you can't be bothered to take the car apart, just look at the chassis number and compare it with these:

Revision 1
December 1989 to December 1991
Chassis JT163SW2000000001 to JT163SW2000059265

Revision 2

December 1991 to November 1993
Chassis JT163SW2000059266 to JT163SW2000087385

Revision 3
November 1993 to June 1996
Chassis JT163SW2000087386 to JT163SW2000106662

Revision 3

(10th Aniversary Ltd Edition)
December 1995 to Febuary 1996
Chassis JT163SW200010????

Revision 4

June 1996 to December 1997
Chassis JT163SW2000106663 to JT163SW2000110780

(Approx)

Revision 5
December 1997 to August 1999
Chassis JT163SW2000110780

(Approx) to End of Production

12/89

-> 12/91 Rev1
12/91

-> 10/93 Rev2
10/93

-> 10/95 Rev3
10/95

-> 10/97 Rev4
10/97

-> 03/00 Rev5