A friend of mine just bought a '99 XC 700. There is about 3/8" lateral play in the secondayr. Is this too much float?

push the secondary up against the bearing on the jackshaft and check primary to secondary clutch alignment and offset. if that is ok then the secondary should move about a 1/4 of an inch out from there and no more. If it's to much remove the bolt holding the secondary and remove the washers desired to get the clearance you want. ;)