These Red Wings were likely made in the late 60s or early 70s, but I couldn't say for certain.

These shoes seem run about half a size large. I normally wear US 10.5D shoes, and these 10D 9335s fit quite well while wearing thin dress socks.

In regards to the modification...

New heel pads were put in by a professional cobbler to replace the original vinyl heel pads, which became warped over the decades. The new heel pads are made of calf skin leather and should be far more durable, and comfortable, than the originals. The original heels pads were warped to such an extent that they couldn't reliably be glued back in without the risk of curling again later on, so they won't be provided with the shoes unless asked for.

It's also worth mentioning there are a few scuffs in the leather, but they're rather minor and should become practically invisible after applying black shoe polish. It's worth mentioning the photos in the listing show the shoes as they are after being treated solely with Red Wing's All Natural Boot Oil, and the sheen of the leather was achieved without the use of a shoe polish.