I have a cone type sure grip in a 489 case with 4.10 gears. I had @RustyRatRod rebuild/resurface the cones and had a local shop set up the new 4.10 gears. All the parts (gears, seals, bearings, etc) I got from Dr. Diff. Also used a crush sleeve eliminator.
I put 80-90 Sae fluid in it with a...