You’re looking for an answer that can’t be proven with information know. Your statement takes the stance there is an alternative. There isn’t.
Cars were built before and after SPDs so you can’t use that as ”last”. A car with an earlier SPD could have been built after a car with a later SPD.
Cars weren’t built in VIN sequence order so a higher VIN doesn’t indicate order.
The VON has nothing to do with production order so you can’t use that.
shipping dates from window stickers may help but you have to acknowledge it would be supporting data, not primary.
Plants did handle broadcast sheets differently. Some plants do use a sort of date code on the BS. Some did use a sequential numbering system. If you can compile BS info, that may help determine a tighter assembly order.
People want order, closure and answers when none may exist.