to find the year of mfg (of the engine at least)look at the serial number right below the injection pump. First part will be the engine model number, followed by a dash, followerd by another set of numbers. The first 2 digits tell the year. The first digit is the year, w for '98, x for '99, y for 2000,1 for 2001, 2 for '02, 3 for '03 through 9 for '09. The next letter tells the month a,b for january, c,d= feb, e,f = march, g,h = april, j,k, =may, l,m = june, n,p = july, q,r = august, s,t = september, u,v = october, w,x = novenber, y,z = december.
For example, my little Z482 has the number
Z482-6A88XX
So it was made in january of 2006. I dont know if this applies to all models or not and sure someone will say if it doesn't, but that is how its listed on my engine service manual.