well for starters,if ur car has all its original badging it should have a series ll badge under the right hand side rear tail light...
if it doesnt have badging you could try deciphering your vin number,located under the front windscreen,passenger side..
a basic code is as follows-
6H8VSK19HVL(then six more numbers destinctive of your production number)
6H8= holden....VS= is the model....K=luxury type (k=executive,L=berlina,X=calais,y= statesman,Z=caprice,theres also s,ss)....19=body type(19=sedan,80=ute,35=wagon)...
H=engine type(H=v6,U=v8)...V=year code(im not actually sure of all the year codes, mines V and its a '96 series ll VS...so at a guess if urs is V or higher it should be series ll)..finally L=elizabeth,S.A.(where your car was assembled)
there's probably an easier way of working out whether your car is a series ll,but thats all i could think of.