Dealing with frame rot
Look closer. A lot closer. The rails rust from the inside out. Don't be surprised if the remaining metal is paper thin. Also check the torsion bar crossmember around the large t-bar sockets. BTDT.
I bought a rust-free complete front clip that included the rails, rad support, inner fenders and t-bar crossmember and welded it in.
Ahhh...the joys of living in the rust belt.