Sealing an 8.8" Ford Rear End with C Clip Eliminators
Ask most people with C-clip Eliminators and they will tell you the housing ends will leak. Those same people will also tell you that there is no way to fix the problem and you are stuck with oil marks in the garage or driveway. Fact is there is a way to solve this issue, the idea was brought up to me by Jared Rude on the Corral, I tried it and it works like a charm. Below are the details and pictures on how to seal up your 8.8 from leaking ever again. This may also work for 33 spline axles but since the diameter of the axle is larger it will require cutting the seal so that they will fit.
Parts:
8.8 end housing seals from 87-93 Mustang. (I
think any drum brake rear end seal for the 8.8 will work but I asked for a 90
Mustang seal.)
Oil resistant silicone sealant.
Brake cleaner.
Rags.
Tools:
3/8 Socket Wrench.
9/16, 13/16, 13mm, 15mm sockets.
Hack saw.
Large socket or anything the approximate
size of the seal (36mm works nice).
Rubber Mallet.
(1) Jack stand.
Floor Jack.
Best way to do this procedure is to do one side at a time with the other side on the ground this will keep all rear end fluid from coming out of the side you are working on. Also make sure not to use your emergency brake.
Install:
Loosen (5) 13/16 lug nuts holding wheel in place.
Chock from wheels to prevent car from moving.
Using floor jack raise the side of the axle you want to begin with and support with jack stand under axle tube.
Remove (5) 13/16 lug nuts holding wheel in place and put wheel to the side.
Remove (2) 13mm bolts holding the brake caliper in place. Slide caliper off and place to the side.
Remove (2) 15mm bolts holding the brake pad mount to the brake backing
plate. Place mount off to the side. Bolts circled as "B" in picture.
Slide rotor off from rear end.
Loosen (2) 13mm nuts from bracket bolted to axle tube. This gets in the way of the C clip eliminator bolts and will make it easier to access them, also a deep 13mm might be needed. See bolts marked "A" in picture from step 6.
Remove (4) 9/16 bolts, which hold the C clip eliminator and brake backing plate to rear end housing.
Depending on how well eliminator and brake backing plate were siliconed on you may need to pull a little bit to break it loose.
Once loose gently guide the axle out of the housing and place to the side.
Using the brake cleaner and rag clean up approximately 2-3” inside of housing end of any gear fluid.
Next comes the modification of the axle seal. Using a marker or pen make
16 marks on the outside of the seal evenly spaced out. Using a ruler or straight
edge here can help out. 
Use the hack saw to cut notches in the outer edge of the seal at each
marked point. As you complete each notch the seal will get weak so if you have a
vice it could help keep it straight. 
With the modified seal place on the inside of axle tube and use large
socket, approximately the same size or slightly smaller than seal and tap into
rear end housing with mallet. Press into housing until there is about 1/2” of
clearance from the outside of seal to end of housing. It can only go in so far
before it hits a lip so you’ll know when it’s in far enough. 
Using liberal amounts of silicone spread around the outside of seal,
sealing up the notches that were cut. 
Clean up any old silicone from brake backing plate and C clip eliminator.
Put some silicone on back of backing plate where it will contact housing and on front where the C clip eliminator sits.
Hold backing plate in place while sliding axle back into housing, it may take some moving around to get axle to slide into differential or spool.
Once the axle is seated hand thread in the (4) 9/16 bolts to hold backing plate and C clip eliminator in place, then tighten.
Line up the brake brace to the brake backing plate holes and tighten down the two 13mm nuts.
Put the rotor back on and re-install brake pad mount using 15mm bolts.
Next slip the caliper back in place and tighten down 13mm bolts.
Put wheel back on and tighten down 13/16 lug nuts.
Raise car with jack and remove jack stand and lower to ground.
Follow these steps again from the beginning for the other side.