60-63 Cab Weak Spots.
 

I don't know if this problem lends itself to the 64-66 cab style but while I was at the paint shop last night, it was pointed out to me that the bodyman cleaned and welded up 2 spots he knew of that were considered weak spots when the cab metal was prone to tearing.

You might was to check this area on your cabs as well.

Re: 60-63 Cab Weak Spots.
 

I had a crack on 1 side of mine that i noticed after cab was sandblasted in the same spot as yours welded them closed. These are difinetly weak ares of the cab.