I think the magnesium ones have a weld spot on the end of the bolt head. So looking at the head of the bolt, in the center, there is a round protrusion sticking out, maybe 1/4 of an inch round.
Look and see what is in yours.
2010 Montana 3150RL
2011 Dodge RAM 3500 DRW, 4x4,6.7 CTD, Auto, 3.73, CC/LB
Line-X Spray in Lining
KSH Tool Box/Fuel Tank Combo