The first loader mounted spear I built had a single spear at the top with two short stabilizer spears and after a year or so I changed it out to two spears on the bottom.  Both of our current loader spears have two long spears down low, one has them on the very bottom and the other is up about 8" because I needed room at the bottom for pallet for carriages so the frame could do double duty.  This one is the last one I built and it has a second set of mounts so the spears can be moved up but so far they never have.  I buy the spears themselves from agri-supply, they are like $40 and work better than the more expensive ones I've tried, I used a 2 3/8" hole saw to make the hole to mount the sleeves in.  We are currently using seven of the agri-supply spears with the first one being almost three years old and haven't broke or bent one yet moving 5x6' bales.  Having the spears at the bottom lets you use them for pallet forks like the others have mentioned.