What Gear Oil For My Dana 60 w/Strange Axles and Spool?

[Oldschool]

I discovered that the ring gear that is currently in the car has a broken tooth. I am going to be proactive and replace the ring and pinion using a new install kit. I am going with a direct replacement gearset. Richmond Gear Pro set  --  4.10 ratio. What weight and type of gear lube should I use. Synthetic or mineral oil based?  Just wondering what the consensus is......  Thanks in advance...   

[Moparal]

I use royal purple in my cars zero weight in my Dana in the Cuda ,  but it is a quarter-mile car only, Road Runner I went to royal purple 80 wait streetcar 354 gears

[Chryco Psycho]

While synthetic has less friction I have heard of numerous problems using syn in diffs so I would use a premium 80w-90 gl4 like castrol

[Oldschool]

We use BG SAE 75w-140 full synthetic in most of the hot rods that come in here. Will that work ok, or should I go a different direction?

[Chryco Psycho]

I am sure it will work but maybe that is why you have a broken tooth ?
There is no need to go to 75-140 IMO  75-90 would be better
http://www.lastgreatroadtrip.com/wp-content/uploads/2010/11/gear-oil-comparison.pdf

[Oldschool]

It looks like 75w-90 it will be.  Thanks guys - I knew I could count on y'all...     

[brads70]

My new Dana from Cass came with a couple jugs of 85w-140 from Lucas if that helps?