I patched mine with sheet metal and formed a new section of drip rail.

I slide a flat sheet in, weld to roof skin, weld to frame. bent and trimed to form new drip rail.

but mine was no where that rusted and it was a 91 cab going on my 85 truck

did I mention it took me from july to December to get it and the floor patched first? and I leaned to weld sheet metal for the first time LOL!

GOOD LUCK! and find paint & body man as your NEWEST BESTEST FRIEND.

that was the best thing I did and now both trucks are painted and rust free.

just purchased a 95% rust free 86 cab from my local recycler for 150 bones to start my gasser truck build.

IIRC there is a 73 cab there that you could buy or chop if interested shoot me a PM.

I know all the glass/doors are gone so chop saw the whole top off for cheap.