Engine numbers

Hello people, can any one tell me what year my XJ900S engine is as when i got the log book back after buying it the engine number was down as not known, the engine number is X4KM 089360X , i have now sent this to swansea but would like to find out if this is the original engine for the 1999 bike, its my first 900s and i have brought it for a trip to spain in june have just fitted new Avon storm tyres today given it a full service and a total one week clean it now looks mint its the blue one with a new Marvin 4 into 1 exhaust, the exhaust is only a mont old and one front pipe is showing the chrome has a few blisters all ready and thats a poor start for the system just cost £512 mild steel and chrome, wish the previous owner had got stainless instead, its fully loaded with yamaha panniers and top box just what i need for the trip, and good tips on the bike would be of any kind would be nice , glad to meet you all, Steve