a-230

The A-230 is a light duty trans. Junk. There is an A-250 that is a "medium" duty trans and is tougher transmission. Bother are Three speeds. I have an A-250 at home sitting under the bench.

None of the transmissions listed except the 833OD will help with your RPM at 85mph since they all have exactly the same 1:1 drive ratio in 4th or 3rd. I would check to see what gears you have in the rear end, and what true RPM you are running at.