PUT A STRANGE S60 IN IT!!!!!!! I went with the moser m9 also, and I am super happy with the quality although its still not in the car, (nice welds and everything appears to be square. I am completely starting from scratch on the brakes for the whole car it should go by june $$$$$$$$$). I called strange engineering a week ago and the tech guy said they quit making the S60 for about a year and a half, and around a year ago had enough demand to start making them again. They have a 9.75 ring gear and come stock with 35 spline axles, best of all you can get one with a spool for under 2k or with a differential for a bit more. I have nearly 3500 in my M9 with brakes and from what I can tell the only advantage is the fact that you can swap gear ratios much quicker and easier. However the S60's nodular iron housing would be stronger than the fords sheetmetal housing IMO.
I would say the S60 is the best bang for your buck by far, my 2 door is getting one as soon as the funds roll in. 8)