If a guy had to go to a hardware store or auto parts store to get pulley to balancer bolts and fan / pulley / water pump bolts...what size and length would he get..?
71 318
5/16-18x3/4 with a lockwasher. Grade 5 minimum.
If you use a fan spacer, increase the length of the fan bolts by the depth of the spacer being used; ie a 2" spacer means you need a 2 3/4" bolt.
Consider using studs instead on the fan if you're not using a spacer, it makes it way easier to get the pulley and fan mounted. Use about a 1 1/4" stud for that- just remember that most automotive studs are a combination NC and NF threads, so make sure you get nuts that are fine thread to use with the studs (5/16-24).