I am not positive on this but i heard they retarded the ports and filled them in more on the '92+ (a little porting will fix that, from what i heard is thay did it to reduce lawsuits). My k5 is a 2001 and it has to most current (for a k5) suspention. i think 2000 or 2001 was the last chang. i know for a fact the 1999 suspention is a lot different than mine. (at least in the US, this is to the best of my knowlage please correct me if i am wrong)
Motorcycle years ar like dog years, most shops will not work on bikes or get parts for biks older than 1997to1998. Even if you find a shop that is willing to help you they may not be able to do to the factory limmiting thier resorces
this may help... i bought my K5 in late 2001 a 50 some year old guy was talked into it at a dealer, but he coun't start it and he sold it to me with one ride (nipples on tires, air filter never cleaned or oiled and no dirt or scratches) for $1900 us
good luck on your search