allied percision also makes a pulling ta 4 disc, in wich i have had very good luck with. It's about 800.00. The sprag, clutch is oversized, they are the same as the 5 disc. I would estimate my tractor at 6to 800 hp with no problems. I also use the 11 spline shaft, the 5 discc will come with the 13. They put a support bearing in the front of the ta.
