I have a 1998 F-150 2wd automatic with a 4.6L.

I am a little concerned about the way the rear end acts when I kick on it. I was wondering if anyone could tell me exactly where to look on the truck to determine the specs of the rear end?

 

There is a tag on the rear end that should have an axle code on it, my tag has a 3 55 9 75, meaning it has 3.55 gears and a 9.75 rearend, your should have a similar tag, but being that you have a 4.6 most likely it is an 8.8. Also, if your wondering your gears here is a chart that should help. Look on the inside of your door jam for your axle code. Hope all this helps you

Axle Type

19 — 3.55 non-limited slip — F-150
25 — 4.10 non-limited slip — F-150
26 — 3.73 non-limited slip — F-150/Mark LT
27 — 3.31 non-limited slip — F-150
B5 — 4.10 limited slip — F-150
B6 — 3.73 limited slip — F-150/Mark LT
H9 — 3.55 limited slip — F-150

 

I have a H9 on the sticker. That is a 3.55 ls. What is more like posi traction? It always confuses me. lol

What would your opinion be if I said I wanted to put 4.10's in?

I just feel that my tranny needs some help. Is that a very difficult transition?

Thanks for your help.

 

are you running a larger than normal tire? Is the truck a 4x4? Are you doing any towing? There are many factors that go into a gear change

 

sorry, didnt look at the first post that close lol....so with your truck being a 2 wheel drive, and a small V8, a 4.10 might be a little much. A 3.73 would be a nice gear for you if your doing some towing, or if it feels like the bottom end is lacking

 

I am running a 265 and it calls for a 235 tire. It just fills up the wheel well alot better.

I plan on buying a new truck before too long and this one will be just a toy. LOL I would like to tub it and stroke it. BUT that is in the future.

I think I will go with that for now, till I make my mind up.

Thank you very much.

 

no problem, anyting to help fellow ford friends. With you runnin a 265 a 3.73 would be a great choice, but if your plannin on tubbing it and strokin the motor, a 4.10 wouldn't be a bad choice if your going to keep the rearend you have in it. Better to make the change now, instead of spending more money down the road

 

What's it doing when you "kick on it" that has you concerned?

 

It is a loud pop, but, I do not feel that would be a good explanation without you hearing it.

This truck has 160K on it, 2nd tranny. This is my wife's truck and she has had it a while. I have spent alot of time REPAIRING work that a garage she went to screwed up. Instead of replacing ALL of the plugs and wires they would only replace 1 or 2, if that helps explain Who has been working on this thing. She was gullable and they knew it!

I have a strong feeling that the rear end needs replacing. I do not like opening up something like that and not replacing it.

 

If you are pretty much convinced the pop is coming from the differential, you may want to change the fluid. It uses 75W-140 synthetic and a bottle of Ford friction modifier. After the change, drive the thing around in circles for 15 minutes to work the fresh lube into the clutches.