front half section of passenger frame horn exterior
top side of front half showing vent hole(s)
inside view of front half of frame horn showing rust pattern and sheet metal seam at mid point.
back section of frame horn before making vertical cut flush to firewall. rust pattern continues along bottom of horn around control arm welded in nut.
after horn cut off flush, here is view inside firewall towards the rear lower control arm bushing mount welded in nuts.. more rust along bottom of channel.
And finally an overall shot showing internally rusted frame horn removal leaving the intact section of passenger side metal.
if a drain is added it would need to be at the lowest point. but probably leaving it all sealed up and full of thick Fluid film sprayed in through the upper frame horn vent holes shown in the second photo will help displace moisture and keep metal from rusting.