Chris,

 A '70 bus can be recognized from a '69 by the side marker lights. The '69 
 will have the round reflector types <like a '68>, the '70 will have the 
 rectangular markers, with bulbs in the rear ones. 

 To tell a '68 from a '69 I'm not so sure. I used to think that a '68 could
 be recognized by the lack of a metal partition between the engine compartment
 and gas tank <you can see the tank from the engine hatch>, but someone told
 me that some later '68s have the partition. There's always the VIN......

 Dave
 '74 Westfalia