I believe there is a 9" ,31 spline, 3.55 ratio axle in my 1986 F-150. Can someone help me confirm this? It is a 5.0 v8 ,4 by 2.

 

for the Ratio and Axle look on the Door Jamb Sticker and Place the axle code. As far as just seeing if it's a 9" or 8.8 look at the back side of the rearend. If it's got a removable Diff. cover it's a 8.8. If the 3rd member removes from the front it's a 9".

 

Thanks for your reply, guess what I'll be doing when I get home tonight! I just need to know what I got 'cause I want to put in some 4.11's. My buddy said we should pull the axle shaft and check splines but F that!


Thanks!

 

if its a 9" made for a truck after 1979, it'll be a 31 spline axle. In 1986, you more than likely have an 8.8"

 

This is really disheartening. I've had my truck for 5 yrs. now, and I have always loved the way it looked/stance. With my engine upgrades and exhaust (lightning style), it rumbles around town and I love to bump the gas pedal and 'jump' forward when I'm going slow like around a walmart parking lot. Only recently have I been thinking about a gearset. Before I found this website or even looked under my truck, I saw in few places it could be a 9". It wasn't!! To my dismay I looked under that truck and saw bolts on my pumpkin last night!! I instantly lost respect for my beloved Ford!!

I have never opened up a Ford axle,or hardly any for that matter. Just recently I helped my buddy rebuild his Firebird T/A or whatever GM calls it and thats where I got my inspiration to up my axle ratio.
So, I got this 8.8" axle under my truck, is there any worth in putting a gearset in this thing or should I start shopping for a real axle 9"? I've seen that a 9" is real easy to work on, is it the same for the 8.8"? I had a '65 stang w/ a 8" and a 3.0gear inside. How can Ford consciously put such an anemic 3.08 ratio in a vehicle meant to pull stuff??
Someone please shed some hopefull light on this small dilemma!!
It's so hard to work in these undersize axle conditions!!!
THANKS!!

 

From what I've read the 8.8 is a good rearend. As for changing The gear set neither the 9" or 8.8" is easy to do. which is better set to a shop so they can be setup right since you haven't done one. One thing off you can screw up the new gear set. The 9" can be bought in a pre-built 3rd member you can slide in yourself. Theres quite a few trucks that come from the factory with high gears such as 3.00:1 and 3.08:1 ratio's. my 86 has 3.00:1 It'll pull anything i put behind it and have a great highway gear. if you got to a few wrecking yards and look around you might come across a good 9" or 8.8" with lower gears like your looking for, Plus much cheaper then buying a new gear set and having them installed. But I'd stay away from the 4.11 ratiio like you stated unless you use your truck for hauling heavy loads all the time. Cause that steap of a gear will hurt ya gas mileage on the road. If you've got the 3.08's in the rear I think you'll be happy with the gain of moving to 3.55's or 3.73's. You'll be able to swap a rearend from 80 til they changed the body style in 96.

 

Thanks for the great advice TX, I feel better already about this thing here. It's not my daily driver, but your right I don't wanna be stuck at 85 mph either. I know a 3.73 is a great all around gear so I'll go with that. It'll be the last set of gears this mother gets, though. One quirk outa this thing in the future and in w/ the 9" (thats what she said)! As far as install goes my buddy w/ the Firebird is a ninja at this stuff, and he wants to know when I'll have the gears.
Anyways, I'll more than likley post about it when I get it done and tell y'all how it worked!

Thanks! J.malone