I find lots of info on swapping 8.8" rears for 7.5", but haven't found anything about swapping a 7.5" for a stock 6.7".

Can anybody tell me whether a 7.5" rear end can be directly swapped into my 83 Ranger with 6.7" rear end, 2.3L I4 and C4 tranny (including parking brake cables and setup, etc.), or are there mods I'll have to make, and what are they? How about the U-joint: will the yoke bolt directly to a 7.5"?

The left axle bearing disintegrated on my 6.7" and tore up the bearing retainer plate; I doubt I'll be able to find another retainer plate easier than I can find an entire 7.5" rear end to swap straight across. I wouldn't want to go to an 8.8" (unless there's no other choice) since it'll probably absorb a bunch of the small amount of horsepower this underpowered 140 CID engine makes.

Some research indicates that pre-'93 rears are the same width although I haven't seen any reference to the 6.7" width. I wouldn't want to go with a disc brake setup since I'd also have to change the master cylinder and proportioning valve as well as the parking brake setup, and cash is extremely limited these days. This 6.7" appears to be a later version of the 6.7" originally used in Ford subcompacts during the '70s such as the Pinto/Bobcat and others, except those generally had 4-lug axle flanges whereas mine has 5-lug flanges. I also discovered the nuts holding the backing plate to the axle tubes are 15mm metric instead of SAE; I doubt the cars had any metric hardware.

Thanks!

 

OK, I found a drawing showing most of the dimensions of the 7.5" rear end, and measuring my 6.7", find that it's the same width and has spring and shock mounts in the same places. Now I need to ascertain whether the pinion snout of the 7.5" is the same; if it's longer which I suspect it is, then I'll likely also have to use another driveshaft. I have the C4 tranny; anybody know whether the 7.5" pinion snout is the same as the 6.7"?? Thanks!

 

why wouldnt you just swap in the stronger 8.8. if you are going to go through the trouble of swapping the axle you may as well make it worth the time and money to put in something as strong as you can get

 

I definitely don't want an 8.8" if I can avoid it. For one thing, my truck doesn't go off-road, isn't drag-raced, isn't stressed in any way at all. I don't even take the RPM above 3500. What I do, instead, is try to spend as little money on gas as I possibly can, because it already costs me $25 per day to get to work and back. An 8.8" is going the wrong way: it takes more torque/power to spin them and most have a lower ratio than my stock 3.08. And besides, an 8.8" will cost some bux that I don't have. My little dinky 140-cubic-inch I4 just doesn't have the moxie to waste any of it on additional friction within the rear end. Heck: when the bearing started breaking apart and spitting out ball bearings, I could feel the extra drag as I tried to keep the truck moving.

 

Finally got the bearing replaced, my newly rebuilt backing plates with all-new hardware installed, and the truck's back on the road again, just before it started raining. I drove it around town long enough for the heater to warm up my toes so I could feel them again :) Turns out the machine shop guy was able to salvage the retainer plate by merely flattening it; however, that did force the mounting holes apart and I had to use a Dremel grinder to elongate the holes till they fit the mounting studs. The bearing apparently caused the retainer plate to stretch.

Unfortunately, I can tell the other bearing is beginning to go out, so I'll have to replace it in a couple months after the weather warms up before this happens again. But this time, I won't have to also replace the backing plates. My old ones were so rusted-out there were holes through the left plate under the brake cylinder and I'd had to use large washers under the shoe retaining pins to keep the pins from pulling through the backing plate.

I still don't know whether a 7.5" will swap directly in place of a 6.7", though; apparently, nobody else has done it. I have a suspicion these 9" backing plates fit either the 6.7" or 7.5" as they were originally advertised on epay for a 7.5" (back then, I thought I had a 7.5" rear).