old u bolts

[swi2]

I have recently purchased a 1 inch block kit from pre-runner greg along with the leveling kit for the front end. I just purchased a new mile marker winch bumper, so i'm about to have alot of weight on my front end and i know it will sag alittle.
I was thinking about taking off the one inch block kit on the rear to even it off alittle.
My question is this, can i use my stock u-bolts that i took off when i put the one inch lift on, i think i remember someone telling me that you couldnt re-use u-bolts b/c they stretch out when you tork them. The ones i took off look perfect to me.