I recently found out my 86 F-150 came with a Towing Package, and it came from the factory with a 9 inch rear end.....so im guessing that means I have 31 spline axels????? can someone clarify that for me????

 

Any 9" 83 or newer is 31 spline, ford quit putting 28 spline axles in trucks in 82, also 28 splines axles are pretty uncommon in 80-86 ford trucks. The towing package means that you have the dual front shocks and stabilizers front and rear.

 

thanks for the info