Most dealers are idiots when it comes to their own products, I'm discovering. If I remember correctly, a VN88 C and L are the same bike. The C/L has different wheels and bars than the A and B. The 1/2/3 designation is the year in the series. Which means (again, I'm doing this from memory) a L1 would be 1994, L2 1995, L6 1996. In 1996 they started offering the Classic 1500 D series (4 speed trans) and E in 1998 (5 speed.)
http://www.vroc.org/wiki/index.php/User:1111/1500a/faq
http://www.vroc.org/wiki/index.php/User:1111/1500a/faq