I have owned dump trucks for years and have relined many of them steel and aluminum. I never used anything but regular steel TWO reasons
1. the cost difference is like 3 times as much as regular steel
2. I dont keep a truck long enough to wear out regular steel
I think the last time I bought a sheet of 11ga. steel it was like $85 and AR was like $220 (4ftx8ft) unless you are really going to haul some rip rap, broken up concrete, etc I wont spend the money for AR steel. If you are trying to do everything first class, then I would go with AR and cut the old floor out. BUT beware, its a bunch of work to cut the old floor out and in most classes its not worth it. I buy all my metal in 4 x 8ft sheets, because its easier to handle
This is what I usually do, if the frames are not beat up
1. Of course, clean the bed out real good and I hope you dont have to replace any frames
2. put a sheet of steel inside the bed longways, by whatever means you have. with the tailgate closed and locked, align the long side to the outside flat/bottom corner of the existing bed
now with the outside aligned, match the end of the new metal to the inside of the tailgate. There is lots of ways to do this, so I wont go into details now
3 with the side and end aligned, tack weld both sides and front end. Do not try to bend the metal on the inside and the front to match the existing floor. I just weld the new plate in the area of the top of the new frames (for inside of metal) make sure the welds are not sticking above the top of the new metal, so the next piece will lay flat
4. After the first piece is tacked in place(worry about the back end at last, unless there will be nothing to weld too, in that case you have to fix it first.
5. Measure from the other side flat corner, too approx 2" on top of the new metal, this gives you about a 2" overlap. This strengthens the joint, tack both sides, making it match the tailgate. If I remember the width of this side piece is about 22" x 8ft long
5a might be a good time to block the tailgate open now, so you can get some ventilation
6. I used to plug weld these to the old bed, but I never saw where it really helped
7. now you should have a 8ft x approx 2ft piece left, cut this to the correct length and install it side to side, overlapping the two new pieces. I try to put the front part of the last piece, on top of a frame, so it can be welded to something solid. The overlap varies on the frames, but it might be 6-8". On a 15-16ft bed, this method should cover all the damaged places
8. Now with everything fitted, you can start welding, I hope you have a mig welder, but I have welded a many one with a stick welder 6011 seems to work better on rusty metal. I just it up to you, if you want to weld 100% down each seam, most of the time I weld all the way, it keeps stuff from getting under it.
9. weld the back end of new floor, to existing floor
As I stated , there is a bunch of ways to do this, but I found it was the best for me. I have sold trucks, with regular steel installed after two years of heavy use and it still was in good condition. We haul rock, sand and asphalt.
This is a long way to try to answer your question, but I learned from the school of hard knocks
Hope this helps someone
Everyone have a good Holidays
