Viggen and nuclear weapon delivery

I have just got done working with an American gentleman who work with DataSAAB during the 1970’s and 1980’s. He talked about walking into a hangar and seeing two Viggens modified for toss bomb sights and precision accelerometers of which he had never seen on any other Viggen. He also mentioned that the Viggen “plug and play” removable box system was utizled by Saab to make a subsystem that, when plugged in, only useful purpose would be nuclear weapon delivery. Any one have any more information on this? I dont really want to go into the debate about if Sweden ever had nukes, thats a whole other can of worms, but i am open to discussion.