If you have a Ford 9" rear end in your street or race car, you no doubt know the advantages to being able to swap the 3rd member, pig, chunk, pumpkin or jackpot easily to change the gear ratio. One of the things Ford almost never installed was a drain plug, I have seen them on some '57-'59 car and truck housings, but almost never on the later stuff. Some of the early housings have a filler on the backside of the housing, but the later housings do not.
From about '67 and up Ford started installing pipe filler plugs on the front of the center sections that can be removed with a 3/8" ratchet. Because of all the variations in styles of housings and center sections, it is entirely possible to end up with a housing with no filler, and a center section with no filler. This is usually discovered at the worst possible time, when you need to put oil in the rear end!!!!! Here is how I remedy the situation and have an easy way to drain and fill the rear end.
I buy a couple of black steel pipe couplings at the hardware store, one is 3/4" NPT for the filler, and the other is 1/2" NPT for the drain. There are cast steel pipe couplings, but you want to stay away from those as they are not as easy to weld. The steel couplings I use are smooth and have no casting lines:
I cut the couplings in half with a hacksaw to about 3/4" in length. You will also want to clean any paint or coating off with an abrasive sanding disc to prepare it for welding. Now is also the time when you will want to cut the hole in the housing. An 1 1/4" hole saw works good, but I use the plasma cutter as I usually cut the holes when I am cutting off all the old brackets.
The factory installed the filler plug at the fill line in back of the housing, but I choose to install them at the top of the housing to the right of the ring gear. I know that a 9" uses 2 1/2-3 quarts of oil, so knowing the fill level is not important to me as I change to oil frequently. Installing the filler up high also reduces the chances of any leaks at the oil line, and makes if far easier when it comes time to pour the oil in :
With the filler bung placed over the hole, a couple of tacks hold it in place and it is welded all the way around:
The drain bung is the same process, a hole is drilled or cut into the housing and the 1/2" NPT bung is welded in place. I cut the drain bung to 1/2" in length. I have seen people try to tap the bottom of the housing, but it is not thick enough in my opinion and I would not want stripped threads in the housing. I like things bulletproof and simple, and this is the best way I have found. You aren't rock crawling, so clearance is not an issue:
A couple of allen head pipe plugs will keep the oil in place.
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Re: Lo-Buck 9" Ford Filler and Drain Bungs:
