[bigblockv6]

Which flywheel measured over 16 inches? Some medium duty trucks do have the larger diameter flywheel and bell housing, that can depend on gvw or tractor application versus flat bed or box van. I only found that true for the late 6500 series which is also medium duty. At one time I did have a 478 flywheel out of a 1963 6500 series with the bigger bell housing yet the flywheel was exactly the same diameter as the 305E flywheel in my pickup truck, unfortunately I couldn't use it because the side facing the crankshaft had a huge crack so that was a grenade waiting to happen and ended up with a custom built flywheel. So as you can see anything is possible.