The 1300's trunk guides on two steel-cored delrin slides. Even brand new bikes had broken delrin molded around the steel cores. Even broken, the delrin still stays in place to do it's job, so you will NEVER find a non-broken guide for these trunks. Being broken is not the issue. And, once in a while you can find these guides on eBay. I just bought a used set (see pics) last week for my project to make a kennel mount for my dog. Although these show broken plastic around the steel base, this is how they also looked new from the factory! Strange thing is, they may crack badly, but none of that plastic ever falls off, so they work just as well (still loose!) as if they didn't crack.
The tubes these guides locate around are .755" diameter, and the point inside the guide where the tube rests, it's .835" wide. The worst part is that they are spaced too far apart, so slotting their screw holes and moving them closer together is the best solution. That will take care of most of the side-to-side twist, but nothing will remove the fore/aft rocking completely. Of course, some all new, redesigned guides could be made to be adjustable in all directions, but how far are you willing to go for that? It's just one of the idiosyncracies these bikes were born with!
Even when new these bikes had what seemed like loose trunks. The bottom of the trunk has a stamped steel plate inside to reinforce everything. You CAN slightly tighten up the guides if you use a Dremel and a drill and carefully slot the screw holes for these slides to move them about 1/8"-3/16" closer together. Just be very careful to move them equally inward or they will cause the locking/positioning mechanism to bind.
These guides also locate the trunk so the locking mechanism works properly. If you make a replacement from a block of delrin, it has to be the same dimensions as original or the locking/positioning mechanism will bind.
I've had three of these 1300's, and even my brand new '83 had a trunk as loose as my current 84 and '85 Voyagers.
