Crankshaft pulley, what is this part?

[quik]

I pulled the timing cover and crankshaft pulley off my 8BA to replace the front crankshaft seal, and this part fell off. I have no idea where it came from. It looks like a spacer. It fits over the crankshaft, but not over the crankshaft key. Anybody know where it goes?

 

[petehoovie]

I pulled the timing cover and crankshaft pulley off my 8BA to replace the front crankshaft seal, and this part fell off. I have no idea where it came from. It looks like a spacer. It fits over the crankshaft, but not over the crankshaft key. Anybody know where it goes?

 

[deuce_roadster]

Looks like a spacer to me. Perhaps needed to make belts line up if the pulley had been trimmed in the past. Are you sure it didn't go on before the key?
Put the pulley on without the spacer or key and see if the belts are misaligned.
It looks too thin to be for a 1 piece front seal.