The point that I should have made in my first post but neglected to is that given you have installed a Mustang II IFS up front, you are obviously modifying/rodding the truck to some degree. There is no doubt that you also intend to swap to a different drivetrain and eventually drive this thing quite a bit, too. If that is the case, you are probably going to find that unless you've got an overdrive transmission, the cruise RPM's of your engine are going to be quite high and your fuel mileage will be proportionately low with those numerically high stock gears. You will probably want a numerically lower gear which is not available for the old Dana axle. Although redrilling the stock axle flanges to match the lug pattern all around the truck is obviously the cheapest solution, do you really want to tie up more money and time in an axle assembly that you will likely find unsuitable for your application in the long term? Careful shopping at the wrecking yards can yield the popular 9" that fits these trucks for around the same money as redrilling your existing axleshafts and you'll have many more options for gear ratios. Just something to think about!