My ignition module on my truck went out and I replaced it but I've come across a problem I can't solve on my own.

When I was taking the old part off, I discovered that the previous owner of my truck must have replaced the part before me. I know this because there were no screws holding the piece in. Only the connector to the distributor. My question to you is what size are the screws that fit in the holes? My ignition module mounts to the front of the distributor.