the seat has been recovered , (of coarse!) the last 490 was the 1990 "a" i think was the model # with the wr500,s following in 92 ,93 possibly 91 in the states but i,m unsure , the only change from the "new style cased" yz465 bottom end through out the (13 year ?) run , appart from gear numbers and ratios, is they shifted the clutch cover dowls on the later ones , my wr cover won,t go on my 465 g , the wr was detuned significantly and is fitted with a smaller carby than a yz and had the same pinging problems, some say a good 250 would eat a wr500 , mine is fitted with a yz cylinder and is lots of fun , the bike i mentioned above also has the same fork seal covers as the one in the photo , but that silencer looks very sameish