Rust trouble spots

[TXPNTCGMC]

Finally decided to start getting serious on the old workhorse. I've started sanding down the paint and putting a temporary primer coat on but I'm trying to find all the rust and trouble spots on the truck before I get any body work done just to know where i'm at.

I dont plan on rebuilding the truck from ground up but i would like to at least get it nice and solid before I throw more money into it.

I found all the usual locations for rust, RH rocker, RH floor pan, it looks like the wheel wells up towards the grill are shot. the bed running along the tailgate and LH cab corner.

Any ideas on where to look underneath or other spots? The frame seems pretty solid, I havent looked real closely yet but I just hate to get it in the body shop and find more issues.

heres a few pics