The Rear Diff fluid had been drained!! WHOOOPS!!! Help
 

Well, it was the first time the car has been driven in 4 years. The car has been in the shop almost 4 years and at some point, some jackass drained the rear diff fluid and replaced the drain plug without re-filling the fluid. I assumed that since there was no rear-end work done what-so-ever that there would have been no reason for someone to drain the fluid. That's what I get for assuming. Now, I am going to have to replace the ring and pinion and all the bearings in the Ford 9" 3rd member. Is there a good set I should be looking for? Is the Summit racing street/strip ring and pinion OK?? And finally, how hard is it to replace these burned out parts in the 3rd member. Is this something that I can reverse engineer or should I just turn it over to a professional? I would like to do it myself and I have considerable shop knowledge and skill but this is something I have never attempted.

Because of tooling not in the average home garage I would guess you will need help. But then again what is average about Cobra guys? You are going to need bearing press plates and a press for starters. You will need a dial indicator with a magnetic base, foot and inch pound torque wrenches and average (there is average again) hand tools.

You can find step by step instructions easy enough so go for it. You might want to have the tooth pattern and backlash double checked by somebody just as a sanity check given the parts investment. GO FOR IT but go slow !!

To properly set the pinion depth and correct pinion preload takes some experience. You must have a vast assorment of shims and be able to remove and reinstall bearings and change various shims in an attempt to get the right gear tooth pattern. This requires a hydraulic press, and bearing clam shells, you'll also need a Torque Wrench capable of over 200lbs and a means of holging the pinion flange while tightening it, A BIG VISE. As mentioned above these are not normally in a "Do it Yourselfers Garage." It looks like the engine you are using is capable of generating a lot of torque. A good tip would be to use a machined pinion bearing spacer instead of the collapsable one that is more commonly available. Getting this machined and fit takes a little more time, but is well worth it. I would defer this entire process to someone that has done it often. Being in the Hotbed of Nascar Racing you should have no difficulty locating a shop that can do this, ask around. You may have a shop in your area that does Rear Ends exclusively, or a shop that does a lot of gear work for 4X4's & Jeeps. It is not a real time consuming job if you have the experience and knowledge. This is something you want done correctly.
Pull the axles and remove the gear carrier from the housing and take it to a pro.