Blacktop Posted November 4, 2020 Share Posted November 4, 2020 Hi all, Looking at doing a gear swap in the 9" axle on my '84 short bed. Will this axle have 28 or 31 spline shafts? Thanks for any info, Alan. Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 4, 2020 Share Posted November 4, 2020 I believe all F150's have 31-spline axles. I'll do more checking Link to comment Share on other sites More sharing options...
85lebaront2 Posted November 4, 2020 Share Posted November 4, 2020 I believe all F150's have 31-spline axles. I'll do more checking If it's any help my 1977 did. Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 4, 2020 Share Posted November 4, 2020 If it's any help my 1977 did. Everything I've found says that axle takes the same shaft as all the others, so it should have 31 splines. Link to comment Share on other sites More sharing options...
Jacob84 Posted November 4, 2020 Share Posted November 4, 2020 Everything I've found says that axle takes the same shaft as all the others, so it should have 31 splines. I have a 9 inch in mine and it is also 31 spline Link to comment Share on other sites More sharing options...
Blacktop Posted November 4, 2020 Author Share Posted November 4, 2020 I believe all F150's have 31-spline axles. I'll do more checking Many thanks everyone for your input👍😁 Alan. Link to comment Share on other sites More sharing options...
Rembrant Posted November 5, 2020 Share Posted November 5, 2020 I believe all F150's have 31-spline axles. I'll do more checking I always thought it was 28 spline for cars, and 31 for the trucks...at least with the 8.8's it is this way. Link to comment Share on other sites More sharing options...
85lebaront2 Posted November 5, 2020 Share Posted November 5, 2020 I believe all F150's have 31-spline axles. I'll do more checking I always thought it was 28 spline for cars, and 31 for the trucks...at least with the 8.8's it is this way. No 100%, I had a car with a nice factory narrowed 9" with 31 spline axles. I found that for a fact when I ordered a Detroit locker from my local dealer. I also am pretty sure the big block pony cars and intermediates got 31 spline axles along with the Galaxies an Mercury full size cars. Link to comment Share on other sites More sharing options...
ratdude747 Posted November 10, 2020 Share Posted November 10, 2020 I believe all F150's have 31-spline axles. I'll do more checking I always thought it was 28 spline for cars, and 31 for the trucks...at least with the 8.8's it is this way. Ranger and Explorer 8.8's are 28 spline. As would be the Bronco II and Aerostar if they ever had it (wasn't an option on the ranger until 1990, which was partnered with the 4.0 OHV Cologne). Link to comment Share on other sites More sharing options...
MarkF100 Posted November 10, 2020 Share Posted November 10, 2020 From; https://www.vintage-mustang.com/attachments/ford-8-and-9-inch-rear-ends-identification-pdf.766989/ A method to identify 28 spline axle shafts can be by looking at the center brake hub area, a rectangular slot in the center will indicate 28 spline axles. The 31 spline axle shafts will have a different appearance, with one small center chamfer and two outer holes in the center hub, however, 28 spline shafts can also appear like this to, so it does not always indicate 31 spline shafts (see photo below). Early axle shafts of the 28 spline variety cannot be shortened, due to either a reduced diameter between spline end and bearing end (early Mustangs, Fairlanes, Falcons etc.), or because of a tapered shaft which doesn't allow for re-splining (early full size).It appears starting around 1967 the 28 spline shafts became more solid and the shaft diameter increased along the entire length, so shortening is possible and they can be resplined to their original 28 count. Most31 spline shafts can be shortened and resplined with no problems. Odd that I don't see your tag in this list. http://www.fordification.com/tech/rearends_ford07.htm It might be of use to others, as it was for me. I don't see where the tag would identify spline count it self. The 9 inch in my 83 F100 came from a 63-72 F100 and has 28 splines. The tag code is WDM-H Link to comment Share on other sites More sharing options...
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