I have a lead on a rear end from a 1968 1/2 ton. The unit is 200 miles away so would like to have a good idea what it is before I take the drive. The PO says the truck is a 6 cyl 3 speed. The service tag numbers he provided are

WOM-U
3,70 8CA 302

Any body know where I can find a decoder?
Thanks

 

O=D as the others mentioned.

 

Thanks havi.

What does a non-locker 28 spline go for these days?

 

HI Frank,

Just fyi and for the other folks too, here is the decoder for the tags:

Technical Articles Index - FORDification.com

Scroll down to "Front/Rear Differentials."

PS Price depends alot on where you live, and how many old ones there are out there in the yards - they are getting expensive out here in California!

 

I found a rolling 72 frame with a 9" rear for $25. The owner threw in four new wheel cylinders with the purchase. Anyone need a 72 frame minus the rear end?

 

My tag was not the right one, disregard.

 

WDM-U = Ford 9" Rear Axle / 8 3/4" Ring Gear / 3.70-1 / 2 pinion conventional (non Limited Slip) / 3,300 lb. Rear Axle Capacity / Large Wheel Bearings / Medium Ball Bearing Differential Bearings.

8CA: Assembled the 3rd week (C) of January (A) 1968 (8).

302 = Assembly Plant Code.

Info source: 1964/72 Ford Truck Parts Catalog / Differential Carrier & Rear Axle I.D. Charts / Section 40.3 / Page 2.

 

Better take another gander at the supposed 9" rear axle. 44-5C is the code for a Dana 44.

All Ford 9 inchers. The rear axle tag code begins with a W.

1959/67 & some 1968 F100's: When Limited Slip was ordered, Ford (usually) installed Dana 44's, cuz the 9" wasn't available with Limited Slip in F100's till mid-year 1968.

1961/72 F100's: The Dana 60.2 (1961/65), Dana 60.3 (1966/72) both w/Limited Slip were optional.

1968/72 F100's: Ford offered a H/D 9" rear axle as an option. The ring gear is 9 3/8 inches.

 

Thanks all for the information.

Can a non limited slip be converted to limited slip? And is there real value or a normal driver?

 

Bill, you're right, I screwed that one up...again. Sorry Frank for messing up your thread.

 

The tag on your 68 sounds very similar to my 71 tag, it was a 6 cyl truck also. Here is my tag:

 

There are a few ways to get a limited slip if your axle wasn't originally equipped with one -

Lockers are a variation on the limited slip design. Rather than clutches, they mechanically lock the axles together in a straight line and then unlock them whe you are trying to go around a corner. There are a few "lunch box" lockers available that will fit into the original open differential carrier. PowerTrax is the most popular. Their products are nice because they are designed to be installed by your average guy in his garage without disturbing the setup of the gears. They have two variations. One is a fairly inexpensive unit called the Lock-Rite locker. I had one in my old Bronco and I think they can be bought for around $250. It's marketed more towards the 4x4 guys as it's ruff'n'tuff. Effective, but noisy when you go around corners. Unless you have no problem with a distinct audible clicking noise and a slight "hitching" sensation when you make a turn, it's probably not what you want in a cruiser. The other product that they make is called the "no-slip traction system". It is based on the same design as the Lock-Rite, but it is more refined and eliminates the clicking and hitching. The pricetag for this improved unit is around $500. Pricey, but there are no clutches to wear out and the gears won't have to be set back up after you install it.

There are several vendors on e-Bay hawking cheap clutch-type limited slip units built in open differential carriers. They have no brand name and there's a good reason for that. From what I've read here and on other boards, they're cobbled together junk and do not in any way resemble the OE limited slip device. Avoid them like the plague.

Another option is a Detroit locker or any of the other numerous name brand aftermarket limited slip units and lockers. They are all nice reliable units. They are, however, all expensive and require replacing the carrier. That means getting the gears set up.

You can also still find rebuilt original Ford limited slip units but they are ALWAYS big money. Many of the alternatives are much less expensive and more reliable at much less cost.

And with all that said, limited slip differentials are mostly useful in drag racing and off-road applications in which maximum traction is a mandatory requirement. I really don't see a need for a locking differential or limited slip on the street in a daily driver or boulevard cruiser. You may get a little right rear wheel spin leaving a light in the rain or on dry pavement if you really get on it, but that minor inconvenience is hardly worth spending the $500-800 it would cost to buy the parts and pay for the gear setup to install a limited slip or locker. Any unit that you buy other than one of the PowerTrax products will require replacement of the carrier and the gears will have to be set up again from scratch by someone familiar with this procedure. This isn't cheap. Now you know why Ford built so few with limited slip!

 

I have to agree with BOR, a locker is way overkill for the street unless you are towing a boat, pulling people out of ditches, or offroading. 3.70 ratio is a good comprimise ratio for a low torque engine and perfect with an OD tranny.