Looking to find out if a rear has 28 or 31 splines in it without opening it up first.

axle tag is S319D 3L50 9 6J02 and it is out of a 1984 Bronco I believe.

I think the code to look up in a factory Service Manual is S319D.

 

The 3L50 would be 3.50 gears with limited slip.
The 9 after that would be a nine inch.
The trucks (and Broncos) used a 31 spline axle.
I forget what the rest of the numbers mean, but one of them will tell you what it's out of.

 

Thanks but I have the basics.

I the factory service manual they have code listings that will break the rear axle down further. I do not have a manual that covers that year but the number S319D is what I need the information for.

Did all trucks in that year have 31 spline axles?

I just found this page Ford Rear Axle Assembly Identification - Page 11 - FORDification.com

S319D Bronco 85-89/Ford F150 Pickup 85-89 3.50 9.0 Locking 31 spline

Says 85-89 but the rear is out of an 84?

When was the 9" last used in the F-series trucks?

 

That axle was probably a mid-year thing, so they used the '85 tag on it. Even my truck, being an '86 has a lot of '87 part numbers on it. All of the 9-inches in the full-size trucks are 31 spline. I have never seen a 9-inch in a '87-up truck, they have all been 8.8s.

 

I believe they first started using the 8.8" in 1983 or 1984 and I have never seen a 9" in anything newer than 1986. Even on the 1986 F150's, most of them are 8.8

 

I don't know what factory manuals you're talking about that would contain this information; I have several for my 1981, the only thing Body/Chassis/Electrical Shop Manual decodes for me is the AXLE codes on the door jamb and a description of what's on the tag (which is different between Sterling & Dana variants).

There is nothing on the tags telling you in which vehicle the axle was installed.

I also have the Final Edition of the FoMoCo 1980/89 Light Truck Master Parts Manual, this thing contains a LOT of information but nothing like you described.

I looked up the S391D last night, it didn't tell me anything you don't already know - it tells me the manufacturer, the ratio, and the Parts List number.

From there, I need to go the Parts List for it, look up the part number of, say, the axles, then go elsewhere in the book to find the details of the axle (spline count in this case) (says 31).

It's not as simple as you describe, there is nothing in the book sorted on axles (or any other component) with corresponding vehicles on which they were installed.

EDIT: I just now looked some more, I can find some information related to Parts List for your axle; it tells me it was installed on Broncos & F150s but not the years.

The stuff on Fordification is helpful but I don't know how accurate it is. At least once or twice I ran into discrepancies between what the books say and what their information says.

In the end, the best thing you can do is pull an axle and count; it's not that hard to do + you'll know it's accurate as you counted 'em yourself. The books aren't perfect, they have errors, too.

 

I have a 1968 manual for my Mustangs and the axle tag codes are broken down as I described above. Been told the newer service manuals did this also.

 

You can go get the same parts catalog I (and a few others on FTE) have for about $20 on hipoparts.com

1980-89 Ford 100-500 Series Truck Master Parts Catalog CD - HiPo Parts Garage