I think the 1P prefix is for early Fordomatic transmission applications, up till the Yblocks used an updated version of them around '55. Doesn't mean they weren't used later in other models but that was the original designation/appl.
The PAB is - I think - a prefix that Ford used for a few years on some of their universal items & wasn't specifically for any year, make or model. Examples might be mudflaps, floormats, etc.
Perhaps someone else can provide a bit more detail.