Let the ride decide wrote:
Assuming that the bags are of the same size,
Material and color were the reason for different part numbers?https://packardinfo.com/xoops/html/modules/partslist/index.php?mode=groupnumber&SearchValue=31.0529&ButtonLookup=Go[/quote]

The V-8 boot bags are made of different material, were cut slightly different and were slightly larger. Remember, it is not just matter of the bag, but the design and material of the boot itself. The last two years of boots (particularly 1955) were made of completely different and bulkier materials and had stiffeners not included in earlier boots.