Ok then. I had alot of problems finding a good set of round towers. As far as I know there is no set of towers that will fit without modding. After fabbing up about 6 pair, I really had gotten fed up. I do feel your pain, but the design is just out dated. Stock traxxas square body posts are the strongest / most available parts you will find. Plus the FLM have available wing mounting holes built in.
I understand dub's point, but in reality it's just not economical. Yes the square posts are better, and if you have to upgrade in the future it is something to consider, but I would just stock up on the stock Traxxas posts for now.
Ebay, $7 shipped w/Each additional item free, they are red but a little black die will fix that.
Or you can get 5/16 or 7mm nylon rod & make your posts. Really they are not that hard to make & I wouldn't ditch a set of Knuckleheads over that.
If you do decide to ditch the Knuckleheads PM me!