I've owned this car for a while now and somehow i've completely overlooked the fact it did not have an overflow tank and there was a bolt screwed into the hole. Since its a fluidyne radiator and its all aluminum, is this repairable? Or should I even bother and just buy a new radiator?

 

Opps heres the pic:

 

Should be no problem welding on a new "nipple". 94

 

all of the aftermarket radiators i have come across have a nipple fitting that's screwed into that hole.

 

If its is threaded, then you can probably thread match a nipple and use some sealant/lock on the threads. Similar to above.