im building a battery mount for 3 200 ah batteries. rather than drill 8 5/8 holes in my frame to hang the brackets im grinding out the rivets for the crossmember (4 front and 4 rear ) and enlarging them out to 5/8. then i dont add any holes to my frame. should save me some time. the L brackets are 3/8 x 4 x 4 angle.