Ok figured this one out! Hole in radiator does require a plug unless you have an aux cooling fan, in which case a temp sensor would be plugged into this hole. The parts guy told me he thought all 940's with turbos had the aux fan. Well mine doesn't. Purchased the plug and as an after thought bought the rubber bushing that the plug goes into. Good thing because the plug was a loose fit in the old bushing. Removed old bushing and it was in sad shape, would never had held the plug, which is just pressed into the bushing. After installing the plug and bushing I secured the plug by installing a nylon zip tie over the plug and aroud the radiator top mount. I would recommend everyone check how secure this plug or sensor is because when it blows out most of the coolant goes with it. I was luckey because it happened to me in front of my house.

JJ