1983 Buick LeSabre 231 V-6 Motor Mount Bolts?

Does anyone know what the bolt type, size, and what the thread pitch is for the front engine motor mounts for a 1983 Buick LeSabre 231, 3.8L V-6 engine? I tried several different sizes with various thread pitches, they all screw in a couple turns and stop. This is for the mount to the engine block. Please email me at: Chevy66@hawaii.rr.com if you know? Thank you for your support, Tommy.