Main difference is mine have the Pro HD case with 3.812 bearings and its a through-bolt case. Meaning the main cap bolts go all the way through the case (see the nuts on mine).
Much heavier duty case. It will handle alot more power and alot heavier a car/truck.
The ones I am selling sell for 1700+ online, then add for a pro gear (another 50-100 bucks).
Thanks for the info. My new 9 inch housing will be done soon and I am in the market for a nice center section. My car won't be making a ton of power but I do want to put the best stuff in it I can. But man that extra few hundred is a chunk of change right now with everything else I'm doing at the moment. I'll give it some thought that 4.86 would be perfect. Though that pro gear worries me as this car will see a lot of street duty.