TIPS ON INSTALLING AN 8 3/4 REAR END IN A GEN II DAKOTA
The 8 ¾ rear is one of the best rear ends ever made. It is strong and lightweight. Best of all, it gives you a better rear end and keeps your Dakota all MOPAR.
It's not that hard, once you have all the info. When I looked into doing this I found guys that had done it, but nobody could give me good details. So I'm going to try and do that here based on my experience. I'm sticking to the Dakota specific install issues. At the end of this, I'll post some links on specifics of the 8 ¾ with respect to housing specs, gears, sure grips, etc.
Some people said A-body, some said B-Body, etc. I used an E-body rear out of a 1970 Challenger. It is about ½" narrower than the stock rear end in my Dakota, a minimal difference and probably a positive in that it makes it easier to run wider tires in the rear. I've seen difference measurement on track width etc. The "been there done that answer" from somebody who has had each of these side by side is that E-Body rear is ½" narrower than a stock 8 ¼ rear from a 1995 Dakota. Other rears may work, but I can tell you from experience that the 70-74 E-Body rears DO work.
You will have to put the spring perches and shock mounts in the proper place for your truck. You can cut the spring perches and shock mounts off of your existing rear but I don't recommend it. P4120074 is the Mopar part number for new spring pads and they'll only cost you about $8. New shock mounts can be made out of steel square stock. It will make for a cleaner install.
The placement of the spring pads and shock mounts is critical to maintaining your suspension geometry and driveline angles. It can change your pinion angle which will result in a wicked vibration in your drivetrain. So, make sure your measurements are good if you do it yourself. Or get someone to do who builds rear ends on a regular basis. Also, you want to weld onto a bare housing. When you weld onto a rear end, you bend it. If you weld onto a complete unit, you can't straighten if afterwards. You want to weld you new mounts onto the bare housing so you can straighten it and then re-assemble. This is the RIGHT way, the PROFESSIONAL way to do this.
What do I do about my bolt-pattern?
91 and up Dakotas are stuck with an oddball 6 on 4.5 bolt pattern. The "classic" Mopar bolt pattern was 5 on 4.5" It is very common, there are a number of choices for rims, and most 8 ¾ rears are in this bolt pattern (A-body rears are 5 on 4 bolt pattern, if you want to use one of those, e-mail me and I'll give you my input).
87-90 Dakotas are also 5 on 4.5 bolt pattern. I converted my '95 Dakota to this bolt pattern. Since the 91-96 Dakotas share the same chassis as the earlier Dakotas, the swap is not hard at all. Your 8 ¾ rear will have a 5 on 4.5 bolt pattern if you use the standard axles that came in it. Moser Engineering also stock 8 ¾ axles in 5 on 4.5 if you want something sturdier. The stock axles are pretty tough though.
Believe it or not, this was the most complicated part of all of this for me to get a straight answer on. I'll start with the front brakes. YOU CAN simple swap 87-90 Dakota rotors onto your front spindles. That's it. That's all. You use your '91 -'96 spindles, bearings, brake components, etc. Just bolt on the new rotors. Here's some handy part numbers for the front swap:
Raybestos Rotors . 7987, you'll need two of course
Raybestos Brake Pads . SSD529, order one set (these are their best "super stop" pads)
Moser Engineering also has a service wherein they will stake your stock 6-bolt rotors, pull the studs and fill them, and then re-drill them for whatever bolt pattern you want. This works fine too and offers you the option of running longer wheels studs, for one. The rotor swap will not work on 4 wheel ABS trucks so you have to re-drill your rotors on those trucks. You can however use the pads listed above.
Rear brakes will differ between rear ends, although again the 5 on 4.5 bolt pattern will apply. My E-Body rear came out of a 1970 Dodge Challenger. It came with 10 x 2 ½ rear drum brakes. I chose to completely rebuild the rear brakes. I used the following part numbers and I ordered them using a 1970 Challenger as the reference. If your 8 ¾ has 10 x 2 ½ rear drums, all these part #s will work. Even on an older vehicle, all this stuff is still available new:
Raybestos Drums . 2947, you'll need two
Raybestos Shoes . 333PG, order one set
NAPA Wheel Cylinders . 37235, order two
NAPA Hardware Kit . 2227, order one
NAPA Self Adjuster Rebuild Kit, Left . 80677, order one
NAPA Self Adjuster Rebuild Kit, Right . 80678, order one
Also, there is a breather in your 8 ¼ rear end that screws in. Your brake lines also connect to it. That will screw right in to your 8 ¾ rear so make sure you save it so you can re-use it. Also, your 8 ¼ parking brake cable will also work with the 8 ¾ rear. Your existing brake booster, master cylinder etc. are okay and do not have to be changed. As for your Anti Lock brakes....
This is an easy one. No. If you swap to an 8 ¾ rear and you have ABS, it's history. The good news is that your brakes will still work fine as "traditional" brakes. You'll just need to learn to pump the brakes on panic stops again. Pull the led out of the dash if the ABS failure light starts to annoy you.
Yes, you can use your existing driveshaft. You will have to have it shortened by approximately ½. When you have your 8 ¾ rear built and installed, you will be able to take a precise measurement then.
I'll breakdown here how you connect your 8 ¾ rear to your existing driveshaft. 8 ¾ rears came with two types of pinion yokes, 7260 (small yoke) and 7290 (large yoke). All Dakotas, at least with 8 ¼ rears, have come with the 7290 yoke. If your 8 ¾ rear has the 7290 yoke, you can simply bolt right up after having the driveshaft shortened. If you have the 7260 yoke, you can get a combination u-joint that will then allow you to bolt up to your existing driveshaft. My recommendation would be to put the 7290 yoke on your 8 ¾ chunk. It's stronger anyway, and makes the driveshaft hookup easier.
What about a Gen III (97 and up) swap?
This is a been there, done that tips page and I haven't done it. Here's what I do know. You can't do a rotor swap like you can on the Gen II trucks. You can however send your stock rotors to Moser and have them redrilled and setup in the 5 on 4.5 bolt pattern. On the rear, there are no up front problems on a '97. You would have to figure out what width 8 3/4 you might be able to use and so on. '98 and up have the speed sensor on the rear and that is a problem. I don't know how you would get around that since you can't relocate that sensor to an 8 3/4 rear.
The 8 ¾ rear has difference from year to year. There are differences in the case (aka the chunk), pinion design and the number of splines may differ, there are different choices of axle bearings, and more. Here are two very good references on the 8 ¾ rear, complete with handy part numbers:
Moparts.Com 8 3/4 Technical Archive
That should give you a good head start on your 8 3/4 research.