Have a '86 Delta 88 3.8 that need to change thermostat. First year fuel injection, unable to find properly sized (diameter) 195 degree thermostat. Anything I can find that are supposed to be correct are too small for opening and will not stay centered thus allowing antifreeze to flow past without doing the job. Need to find something to center the thermostat in hole. The one's listed either have way to thick a gasket around outside will not fit in hole or without gasket allow to have antifreeze flow past. Strange deal, any suggestions as to proper part number ?