differeneces in kx500 engines, help me id this one

[KXT500]

i just bought a kx500 engine and have no idea what year it is. how can id it??
thanks
chris

[GREENCANNON]

not many changes over the years I have an 01 and my buddy's is an 87
his motor is black, mine is silver. His has a paper top end gasket, mine has a steel one. His sproket is held on by a locknut and washer, mine is a circlip. He has a two way powervalve, mine has a three stage.
I'm not sure of the cuttoff years but I think it's from 86-87
88-95 and 95 to 03 changes were made....
somebody correct me if I'm wrong
If all else fails use the numbers off the engine

[KXT500]

well if i get a picture can you tell? the numbers onthe engien are half gone. well the ones on the left  case by the cylinder base are. it looks liek the stamp was cock-eyed when it was stamped. the engine is black but the sprocket is held on by a nut???

[GREENCANNON]

These are all    the features I can think of that this 87 has.

KIPS logo on left side of cylinder is glued on, the kicker is a flange head bolt ( not an allen bolt )
A mikuni vm carb, paper top end gasket, no locator or dowel pin for head and cylinder. no third exhaust valve over the exhaust port. you can tell by removing the pipe and looking in.
send a pic