Welcome to the new and improved Proflex / K2 Tech Forum!
I have an XP-8 (which is a UK-only version of the 856) from 1996 which originally had the silver vectors. I dropped in some crosslinks no probs. I think the ride height is altered by an inch or so, but that's fine as I'm lanky anyway and the saddle has to go so high it's great the handlebars can come someway to meet it! You get different versions of the crosslinks though that cater for different headtube lengths - I think there's a Standard and a Long - forget what measurements they deal with though. I think most proflexes of that time use the standard fit.I bought 2 pairs of crosslinks from the States on Ebay, for about $100 each, but by the time they were shipped over and I paid tax over here in the UK they came to about £85 ($145) each.
I rode my smartlink (not) tonight. All the oil is puking out, so it is actually working preety smooth. When it is empty, I may saw of the battery and drill in a grease fitting.Look for a conventional damped carbon crosslink if you can find one. But the smartshock version works and can be upgraded with many kinds of aftermarket shocks if you hate it, as well as noleen shock service selling off old stock.If you do end up with one, pulling the smartshock is a pain as you have to dismount one or the other link. But the trick is to drop the wheel, unscrew the preload disk, unclip the springcap and jockey out the spring. Compress the shock and now it can be wiggled out( the battery case gets in the way of everything). If you need to keep your vector, Risse racing makes a nice genesis shock for it. Terry