According to my calcs, it's  2 3/8 wider than a 65/66.

BB

From some searches - yes.  You will need new perches from what I read since the spring spacing is different.  For most of the Explorer rears with 31 spline axles, the axle tubes are 3.25" which will require new/different spring plates (perhaps the plates for the 9"/big block cars) and u-bolts.  The Explorer pinion is offset but apparently on the 68 the driveshaft will still clear the back end of the seat pan but I have have seen some postings that indicated some hammer management was needed on lowered cars.  The Mustang 8.8's are centered and are the same width but are 28 spline.  I think the slight angle that the offset pinion adds to the total u-joint angle is still within reasonable limits.  Find a 3.73 TL 31 spline and you're good to go.  But, given the ease at bolting in an 8", I wouldn't hesitate to bolt it in for the time being until you locate an 8.8 (unless you already have one).  One pretty good idea I saw in a posting was to install the rear with the new perches without welding them.  The rear can then be rotated to find the best pinion angle for the car on its own springs.  The perches were tacked and then the rear was removed and fully welded.  If you have a good surface to work from and a digital level/angle finder I think it may be just as easy to match the 8.8 to the 8".

The guy that built my 9 inch rear end said that he used Mopar spring perches because they are thicker and heavier duty than the stock Ford ones. Just a thought..... if you do need to re-position your perches.

MS wrote:

Wondering if I am jumping the gun sticking a stock 8" in there.

 
For a street driven vehicle I would not hesitate going with the original 8 inch, even a peg leg one.
 A  Ford 8 inch rear end done with quality components will handle close to 400 HP, as you don't make a habit of leaving your signature too frequently.
 The 8 inch behind my 331 with an Auburn gear traction control has performed very well all these years, even with the occasional  bouts of adolescent behaviour.

Last edited by Rudi (1/23/2016 10:23 AM)

Heck, Corky could have ended up on top of that red vert....no problem.

BB

I installed an 8.8" rearend in my 68 Mustang. The 8.8 came off a 2000 mercury mountaineer (suv). I looked at the mileage on it in a salvage yard and identified the tag to make sure it had 3.73 gears and a posi. I had to weld on new spring perches. I set my pinion angle and then welded them. The shock mount was different from my 8" rearend. The entire rearend was $200 from a salvage yard which included the rearend yoke, complete rearend, and disc brakes.