Welcome to the new and improved Proflex / K2 Tech Forum!
Proflex 756 with springs...I thought the 75x had MCU/elastomers in 1996, but the shocks look like ODS upgrades...Frame size is M...http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180241000640&BackToListReferer=http%3A%2F%2Fmy.ebay.com%2Fws%2FeBayISAPI.dll%3FMyEbayBeta
thats a odd bike...the 857 would have had a carbon swingarm,that looks like a 757 swingarm,and the forks look like they are vector legs on a crosslink linkage.....Not saying its not worth pursuing,...