This is a duplicate from alt.home.lawn.garden - I did not know the best place to post it.
I am replacing the panels on my fence because of rot and lack of integrity (1 x 3 cross pieces). It is currently 4' tall and I am installing 6' panels. The posts are cemented in and in good shape - I would like to keep them. They are on 8' centers. What would be the best method for adding 2'+ to the posts? I was thinking I could toe nail (least desirable) but I could also use some square metal brackets on 2 sides (not bad) or several wood dowels (time consuming - there are 45 posts). I think the best and cleanest install would be to use (if it exists) a screw that is threaded on both ends. With a couple pilot holes I could screw into the extension and then twist the whole unit onto the existing post. The panels have 3 cross pieces and since 1 would fall on the extended piece it should keep it from ever twisting.
My question is what would be the best option as far as stability, ease of installation and aesthetics (in that order I think). If my screw option is the best - do those exist and what would they be called? Does anyone have a online resource for that stuff? Are they made big enough?