So after a bunch of searching on the forums, i found bits and pieces of information, but no real step by step walk through of doing this swap. I figured i'd put one together for those who want to undertake this project in the future. The task isn't hard at all if you know your way around a vehicle, and with some patience and common sense anybody could get this done. So on with the how to....
Picked up an 2008 8.8 rear end with 4.10 gears and a limited slip. I think it came off of an fx4 because of the rancho shocks, it also had 10" drum brakes, unlike my 9" drums on the 7.5...here she is in all her glory.
Next i needed some backing plates, so off to ford i went to pick them up. I just explained to the parts guy what i was doing and i needed the backing plates to fit the bigger diameter axle tube from the 8.8. Being that there are only the 2 plates for the ranger, we chose the one with the bigger distance between the u-bolt holes, and they worked perfect. i paid 30 dollars for both plates, thanks to my buddy who's a salesman at Ford. Down the street i brought the backing plates to a spring shop, and they bent me up some new U-bolts to use with the new axle.... 40 dollars. Not too bad...here they are, not completely tight around the axle, but when the impact gun hit them, they wrapped tight right around the axle tube
Next was to paint up the rear end. Some flat black rust spray will keep it looking good for one season. The salt belt will take care of my paint job. Looks good for now tho
On to the real work. Before i took anything off the truck, i went to my local part source and picked up some brake lines, as i knew that the current ones would be so rusted i wouldnt be able to re-use them. A flare kit for the lines, and some brake fluid and gear oil. Check the tag on your rear end for the specific fluid, i needed 70w140 i believe. synthetic because of the L/S. I got all my tools out, nice and organized so i wouldn't be running around like an idiot during the process.
Jacked up the truck and supported it, i didnt like only having the two jack stands on either side, it seemed as if it wasnt enough. The jack stands were just over the halfway point of the truck, so i put one more jack stand under the hitch for added support.
When i had the truck in the air, i took off the wheels and rusted drums and took apart the brakes. You have to do this in order to release the ebrake cable off of the 7.5 rear end.
the cable is held in by some clips, just use some needle nose pliers to squeeze the clips and pull on the cable from the back of the brakes, it'll come out..heres the ebrake cable
next up, just disconnect the shocks, one bolt on either of them.
next I unclipped the abs sensor harness, so that the abs sensor itself is still in the axle, but the harness is free..also the brake lines can be disconnected at this point. as well as the drive shaft. only four bolts on the driveshaft, it will want to spin, but you should be able to break them lose. drop the driveshaft and put a piece of wood under it, you might have to tap the driveshaft with a rubber mallet to get it loose. the picture is of the brake hose t connection on the top of the axle. Keep this in good condition as you will be running your new brakes to this connection
at this point i got stuck because of the rusted brake lines, so it was a good time to clean up the new diff cover and add some black gasket goop on it. i used brake cleaner to clean it and some rtv gasket maker.
Back to the 7.5 getting out from under the truck...I finally got the brake lines loose! supported the rear end under the diff and unbolted the ubolts. I slowly let it down onto blocks of wood and pulled it out from under the truck. Be careful here and use some common sense. The 7.5 isn't too heavy, but it does want to dive down nose first (where the driveshaft hooks up) just go slow and you'll get it out. i got it out on my own, dropped it onto an old carpet and pulled it out.
ranger with no rear end
the old 7.5
i did the brakes on the 8.8 and ran the ebrake cable through. By this point everything should become apparent on what to do.
take your old abs sensor out of the 7.5 and place it in the 8.8. They break easy, so be careful. I took mine out by placing two screwdrivers on either side of it, and pulling up. I pulled the whole 7.5 off the ground by the abs sensor before it came out. But it did come out in one piece. One thing i found on the 8.8 was to fill it through the abs sensor hole. you dont require one of those pumps this way. i put the axle on level ground and squirted 3 and a bit bottles of gear oil in it. Then i opened up the filler and let the excess leak out.
line up your new rear end, jack it up, throw the ubolts on it and reattach everything thats not attached. make sure your backing plates are centered on the centering nuts on the leaf springs. theres no real way you can mess this up...just pay attention and dont install it backwards. bleed your rear brakes and you should be done. Make sure everything is tight! dont forget to check everything! Have a breaker bar and a lot of PB blaster. A big set of nuts helps too, only real men can crack bolts loose in the rust belt.
I drove to my mechanics afterwards and had him hit all the bolts with some air. That tightened everything down to the point i felt confident driving down the highway. There you have your new rear end. I couldnt be happier with it. Hope the walk through helps.