Thanks to everyone for the reply and information!
This is what I learned so far:
1. The seed distribution method of a Bluebird or Billy Goat Over-seeder is very inaccurate.
2. Drop spreaders are more accurate then broadcast spreaders. My almost classics, 24 years old Scott’s PF2 drop spreader is most likely as accurate as any on the market today.
3. The spreader should be calibrated prior to use to ensure accurate seed distribution.
4. Seeding an acre 43,560 sq ft with a 20 inch wide drop spreader is a job for the wife.
5. If the seeder is in the front of the over seeder – the seed will be sliced in the soil.
6. If the seeder is in the rear it will be distributed on top of the sliced soil.
7. It is recommend applying grass seed in 2 directions - North-South then East-West
8. Kentucky Blue grass is the best spreading grass.
Stay in the fight for Christ!