This is an early Chevrolet smog pump. 

This pump is in nice condition and will work great when cleaned or restored. 

I can do the restoring of this part for 150.00 if needed. 

Here are numbers on casting 5696211 cfb1 possible date code of 66as I see a 66 marking there is also a 29161c and on rear case I see d10 5696132 please ask any questions. 

Thank you