What do you guys think of this rear frame rail...rusted too bad?

[TireSmoknWindsr]

Sorry for pic quality but I didn't have much opportunity for a fancy nice shot. Does this frame rail look too bad to you? Think it'd be alright for another 2-3 years or so? I'd imagine so but wondering. For a '66 how hard is it to replace that anyways? Could I do it just by drilling the welds, cutting the rear part of that frame rail out and weld new one back? Or is it alot more difficult than that?

http://www.mustangmods.com/data/7433/framerail_013.jpg
http://www.mustangmods.com/data/7433/framerail_014.jpg

 

[67GTFastback]

It looks very similar to the one on the coupe I am doing. It could be driven on for a while I am sure, but obviously you want to fix it when you can. I have this car completely disassembled right now though and need to replace the tail light panel and rear cross member anyway. I am just going to cut it out and weld in a patch.