You have a 40's truck?
If you replace them mild steel is probably fine, depending on use. The original was probably a better grade of steel though.
I have not replaced those plates, but I did replace a bunch of 3/8" rivets in my 48 2 ton frame.
It is not real simple, but not impossible.
Would be nice to have the proper tools, an air powered rivet hammer with the correct concave die/punch to form the rivet head.
I made my own die/punch, or what ever you call it, for use in an an air hammer, Also made a heavy piece of steel with a concave to fit the rivet head and back it up while forming a head on the other end with the air hammer.
It worked good for me, takes two people, one to hold the backup piece, called a rivet buck, and one to heat the rivet held with a pair of tongs in front of the torch to bright red heat, install it, and form the head with the air hammer.
I have been told that a true rivet hammer acts different than the air hammer I used, and would make the process easier.
Grigg
