Eureka! - I think mk nailed it. Now I remember, you are holding the "bolt" holes for the driveshaft center bearing support. If you remove those bolts you can actually slide that piece out of it's housing underneath the car. Look underneath the car and make sure this part is supporting your drive shaft. If they are then you are probably holding the ones from the spare. I suspect they built it like this to allow a little alignment adjustment in fastening the carrier bearing and to allow ease of replacement if you ever strip the threads out.

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Jim