the 60 diffs WILL go straight in BUT, they have 3.70 gears rather than 4.11s- you'll go faster down the road, but slower up them hills. AND, I don't think there was a year of 60 flange that matched pre 78 flange. you could get some solid pinion spacers, and some transition flanges from Marlin Or Curt Or ...I think I have also heard that you could mix and match drive shaft yokes to match the flanges YMMV...the thing with the solid spacers at the pinion is that the 60 diff uses a crush sleeve to get/keep preload on the bearing and if you don't crush it right, it's not good. when you go to change the flange, you have to get the preload just right- a used sleeve has potential to crush too far. the solid spacer(as used in earlier diffs) and the shims that may be in there from factory, are easy to re set. When going from crush sleeve to spacer, just check preload of as-is donor diff and make sure there is no excessive play and that the preload is in spec. the take apart the stake nut, washer, flange, seal, bearing and crush sleeve and use the height of the sleeve as crushed with proper preload to set the height of the spacer, then shim as needed to get preload as it was. NOW, I have been told you can r and r the flange on a sleeve diff if you are very careful getting matching load before and after when using the same sleeve and bearings. Drilling is a viable option. I may be making a much bigger deal out of it than needed. you will have to remove the read diff cover, pinion shaft lock pin, pinion shaft and spacer, c clips from the inside ends of the axles as viewed looking into hole in diff carrier(push axles inward and remove clips, pull axles straight out carefully-new axle bearings and seals...brake components?)) you will need new diff cover gasket, or use grey diff gasket maker(works good) I used grey on my thirds and no leaks. front diff>get off the hubs, spindles, withdraw axleshafts.
