I have a 2004 F-150 4x4 Crewcab. I want to know what axle size I have (i.e. 8.8, 9.75 or 10.25 inch) How do I find out the axle size?

 

Get under the back end and count the bolts that hold the rear cover on. 10 bolts is the 8.8 and 12 is the 9.75...the only way it'll be the 10.25 is if you have 7 lug wheels....also i don't think the 10.25 came in the crewcab model.

 

Thanks! I have a 10 bolt so its a 8.8 Is this the same for the front axle? How do I determine the axle spline for the shafts?

 

The front is a reverse cut 8.8. 28 splines in front and 31 in the rear. Lockers????


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Thanks for the info for the front and rear splines. I am considering lockers but do not really know which one to choose? The truck will be mostly be driven on the road with the occasional weekend detour. Any suggestions?

 

I do not know how deep you go into the woods so I will suggest a Detroit Truetrac for the rear and nothing up front. On slippery surfaces with both front wheels spinning you loose steering control. In the slop that is OK because you are not going that fast. On the street you need precise control at all speeds and when both wheels slip........


Regards

Jean Marc Chartier

 

I'll second the Detroit True trac, (I have one in the rear of my '08), but I'll go one further. They work tremendously well in the front axles as well. I'd put the Truetrac in the front, and back, unless you want a full locker in the back. Don't put a full locker in the front unless it's selectable ie. E-locker or ARB.

And for the rear, if you do want a full locker, I love the Detroit Locker I have in my 1996 F350. They call them soft lockers now. They don't bang and clang like they used to, and the road manners are just fine for everyday use. I tow with it, drive on the highway, around town, you name it. I'd do it again in a heartbeat.

 

Tahnks alot for the help and advice. The true trac seems the way to go for my application. Another question I have is what gear ratio should I run for 37in tires since the axles up front is 28 spline and the rear is 31 spline?

 

What is your current tire size and axle ratio?

Regards

Jean Marc Chartier

 

I'd be going minimum 4.30. Probably be better with 4.56's though.