metal thickness

i have a 90 mighty max im doing a underslung back half on and i want to go with a 2x3 or 2x4 on but i was wondering what thickness i should go with?
But ive heard ppl use 1/8 , i plan on plating all the welds,
they only reason im even considerin using some thing less than 3/16 is because metal cost these days.

heres where the new fram will start...


and my set up will be kinda like this ....do not laugh at my weak paint skills...lol

2x3 on that small of a truck and it being a back half is fine. I've seen guys use 1/8th with fine results but ive always used no less than 3/16. If your looking at the cost difference its not to much more expensive unless ur a contractor buying a mass amount then size difference may start to add up. But I'm sure youll get a few more comments so this is just one IMO to you and good luck on the build with what ever you go with

.120 wall is fine. I'm pretty sure thats mostly what Max uses. That is what I use on backhalfs. However I do like the more rounded corners of the .188 wall tube. If the price difference is close enough when I am buying material for a backhalf I will get .188 just because of the look. Its not necessary for strength though really.

And a word of advice, turn the welded seam to the inside of the frame. It shows up after you paint it.

and if i do 1/8 plates i would be ok also?

Yeah. I generally use 1/8" for gussets and fish plates, etc.

ok cool thanks!

.120 is fine, but I would still suggest bracing the area in the frame where the cab and the bed meet so that you don't have so much "bed sag" when you air up the truck.