How do i tell what year truck i have - without a body?

[sanderbing]

I purchased a truck recently that has a 53 body but the chassis, I was told, is a Chevy 86 3/4 ton 4X4. But while fixing the parking brake, i could tell by the diagram at LMC truck that the cables in place were from a 83 truck. But the wheels are 16 which agrees with the sellers claim it is a 86. IS there a way to find a number on the chassis or something to determine what year this really is? Thanks in advance for the help.