This is one an other is brass mono block w/7/16 shackle.
I think the best might be the"hidden shackle" type. One below is from Grainger.
Make sure they will fit on the doors of your truck. All types can be keyed alike
High Security Diskus Padlock,Silver
Item # 3TMP9
Keyed Padlock, Diskus, Security Level Extremely High Security, Key Type Alike, Body Material Stainless Steel, Round Shape, Color Silver.