My 4/89 built 535 is the same. I forget which relay has 4 pins and which is 5, the 5 pin can be substituted for the 4 pin, but not the other way. The 5th pin is a normally closed contact the 4 pin doesn't have.
These are standard relays and can be had for a couple bucks a piece if you browse the local parts stores electrical suppliers catalog rather than ordering for a specific application.