My Drag Blocks!!

my buddie made these up for me at work with 1" thick steel. there 1"x3"x7.5" steel. I know some ppl mite rag on me for not dragging my frame instead... i did that and theres not much left how long do you think these will last? there pretty hefty. Im bolting them to the front crossmember on each side. My buddie corved the front like skis so that incase i snag a bump.. it wont rip the crossmember off, it will just feel like a bump.