This is a 5000-lb truck, will be running 38's or 39.5's. Was planning to swap in a 70, but the one I got is a bastard axle. 70-3 HD (-U ?) "aerodynamic cab" with 31/32" pinion offset. Only gear option to use the Power-Loc carrier in it is 4.56; only other carrier option is Detroit 225SL58E, which has a larger offset to use standard 4.56-down D70 gears in this POS housing. My 60 rear (30 spline open diff) already has 4.10's, and the 35-spline axles out of the 70 are exactly the same length as the 30 spliners in it now - just need to get reamers. Also have a set of 35-spline side gears for an open 60 carrier. I know the 70 has bigger brakes and is stronger throughout, but how many people break 35-spline rear 60's that wouldn't also break a 70? Is the strength advantage of the D70 worth ~$850 in gears, bearings and detroit? The 60 has a tad more ground clearance, but not much. Thoughts, comments, suggestions?