I rented a Frontier 58 inch over seeder from Sunbelt Rentals. http://www.sunbeltrentals.com. I am three years into my new lawn and it was very clumped and sparse. I am hoping the PTO driven over seeder will aerate and fill in the voids of my current lawn.
The seeder was heavy - so I was glad that Sunbelt would just load it on my trailer.
Unfortunately, when I got the seeder the drum was full of string, netting, plastic mesh and even barbed wire. It took me two hours to cut all of that crap from the drum. The picture above shows my progress half way through the job. Sunbelt did give me half off of the rental for my trouble.
Four hundred pounds of Rural King grass seed later, I had my three acres overseeded. The results were pretty good. I was able to break up some grass clumps and seed my bare spots. Hopefully the grass fill in properly.