thickness metal for floor, cabwall, and firewall?

any suggestion on what metal to buy for my floor?

back of cab?

firewall?

i would say 12 thru 16 ga you want it thick but not to thick

I used 16 ga for most of my floor and firewall. I cut a hump out of my rear cab wall and plated that with 12 guage.

12 ga. is pretty thick about .100 I use 14ga. for the floor (.075) and 16ga. for any walls(.060).

16 ga. thats what i use for everything

i used 16 ga for everything and used 1x1 for the supports

i used 16 ga for everything but dont forget about supports

when you get repaair panels for nearly any old car with rust floors it will be 18-19 gauge 1018 cr steel. 18 guase will be absolutly cool for you floors and firewall as long as there is some shape or you roll some beads. If you want flat then I would go thicker and support the crap out of it.

got 16g...floor is about 75% done

Glad to hear you went with 16. Your panels are 18, and are too damn thin to begin with.
Post up some pics.