How do I measure flywheel to see which one I have??????

small block flywheels in light duty trucks were the same as small block car flywheels. If it has (from my recollection) 130 teeth on the ring gear it is a small block 10.5" clutch flywheel. The last one I bought came out of an early Dakota V6 - same as, even down to the part number on it, a 69 340 flywheel. The 360 ones however had some balance holes drilled in them, but you can take a non drilled one and drill the holes to work behind an externally balanced 360.