Does anyone know the difference between the Cali and Fed vacuum advance modules on '87 22r engines and if they are interchangeable?

I've got an '87 4x4 truck w/ 22r. It had all the Cali emissions crap before I put the Weber carb on it, now all that is gone. A local store has a Fed emissions vacuum advance but I have to order the Cali. The Fed is cheaper but if it won't work it won't do me any good and they are too expensive to buy two.

Thanks

 

No one has any ideas?