So Ive read a little about final drive ratios and from what I see a 3.50 or 3.55 is a nice all around rear.

I want to go posi and have a nice all around truck for light off road and freeway travel. Country ride basically. I have a 4 speed where 4th is labeled "od". Currently my rpms on the freeway in od are nice and low. I could stand them to be a little higher. Should give me a slightly better take off and stump pulling but not sacrifice gas milage in my 4.9l currently 3.08 rear factory tires at 28.9 inches tall.

Any input would be much appreciated. Thanks ya'll

 

I think you are right on the money with the 3.55's. I have 3.73's in the F250, which will see towing duty. I will leave those and find a nice posi for the Dana 60. The Nissan has 4.9's in the rear and it accelerates well, but tends to rev high on the freeway. Also, the Nissan is only a four pack, so it needs those tall gears.

 

I agree that the 3.50ish range would be the sweet spot for your truck.
If you have the 9" rear, you can get a complete third-member from the Bronco Graveyard (or similar place) where it is just a Saturday afternoon bolt in project.
1980-96 Ford Truck/Bronco Ford 9" 31 Third Members & Parts - Rear Axle Ford 9"

 

Actually I have the 8.8, But I have another question. A friend of mine offered me a posi set for a 8.8 rear but its for a 2000 model rear. Will that fit? Im no good inside the pumpkin so I would need a nicely done guide to swap it out.

But that would be sticking with my 3.08 which I dont like very much. 1st seems a little luggish lol if thats a word.

 

You need a ring and pinion set to install. Take the posi, have the new ring and pinion installed, then you will have what you want. If you are not comfortable doing the swap, have a shop rebuild the pumpkin, then install the completed assembly.

 

I looked up a ring gear set online and that's fairly costly.
Would it be cheaper to just find the rear I want at a junk yard or something?

Not too sure about the cost of it all yet either.

Loving the input thanks y'all!

 

It would be much cheaper to find a 3.55 limited slip axle from a local yard. 3.55s were the most common ratio equipped in the 1/2 tons.

 

Well I talked to my buddy again and he has the gears too. They are new we just need to look at them to see the ratio. Hopefully its the 3.55 setup then I may just be able to use his parts.

 

Coolness! The gears he had are 3.55! Ive got the entire set home now and ready to get installed. Seals, bearings and fluids. He was going to upgrade an old truck of his but decided to sell it so he gave me the parts.

 

If you're swapping gears yourself, make sure you know what you're doing. It's really important to get them set up correctly (at least if you want them to last). Most of us have never done it ourselves. It doesn't sound like rocket science, but it's not something you go at with just a set of wrenches and a can-do attitude either.

 

I've setup a couple rears and they are a PITA in my opinion. There's a local shop that charges $350 and it's well worth it. BTW, none of the rears I set up have made noise or blew up, so I must have gotten it right...

If you do it yourself you will need a few specialized tools. Most importantly is a dial indicator with magnetic base so you can measure the backlash. I tried playing with a pinion depth tool but it was too complicated for me and I just threw the stuff together and went for the best pattern I could see. Then check the backlash and if it's within spec you're good. Also, you'll need a bar type inch-pound torque wrench to measure your pinion preload.

Have fun with the crush collar... And have a few around. And gear oil STINKS! Did I mention that I pay someone else to do this now?

 

Did he have the 3.55's already in the carrier? If so your swap will be simple. Check the backlash anyways, just to be sure. And that dial indicator is useful other places as well, like the brakes.

 

3.55 is a pretty good gear. But I like 3.73 better. Unfortunately they were not a factory option in these trucks

Like others have said, setting up gears is NOT a bolt in deal. You need to check back lash, preload and wear patterns. Better left to a Professional. Also a press is , dial indicator, inch lb torque wrench and gear paint in necessary

 

To be honest I dont know much about rear ends. If the carrier is what I think your talking about then yes.

Ill post a list of stuff he gave me a little later today. There are bearings, rings, gaskets and seals. Along with the ring and pinion set and carrier. I looked it all up and this is like 600% worth of stuff. I owe him a huge thanks.

I am pretty dang good under the hood so Im confident that with he right guide I will be able to get this installed correctly. I do have both the chiltons and haynes manuals along with the internet I'm sure I will be fine.

 

I assume you are refferring to the F100's and F150's. I have factory 3.73's in my 81 F250 but it is an open diff Dana 60.