Going to look at this jersey in detail.
I believe this is a 1983 retail jersey. It's a small kids size but it's a good representation on the types of supporters jerseys that were available back then. Although it's impossible to narrow it down to a specific year. From what I've looked into though there were no replicas sold at that time with sponsors and most jerseys that were sold as replicas were sold in kids sizes as it wasn't the done thing for adults to wear replicas to games.
Not going to be adding this to the main site, have something similar from the same period and this is too small to fit onto the mannequin!
This is made by Peerless but has the 'Junior' tag on the Peerless logo and a previous owner has added the "1" on the back. In 1983 there were a number of players who played fullback, Ron Sigsworth, Tim Barnes, Paul Morris, Greg Brown so someone was a fan of one of those.
The other interesting thing is that the Jets badge has almost straight sides, unlike now that the Jets badge is almost a complete oval shape, back then it was almost a diamond shape. Have no idea why the shape changed but of the two I personally like the old shape.