i think if you have 3.73 and u still boge down i think its time for a new motor i got a 300 with 3.55,33.12.50 and i can pull digg sling turn what every you what to call it.
i got a 78 150 4x4. that im giving up the 9" in it to keep my 8.8 pois. i went out today and went more places than 4x4 and im 2x4 so if you r scard let me nkown i might cut ut saome slack. you gus are a bunch or nerds if you buildm a bick ind one week and still gett your money call me bitch if you want thio

 

were you drunk when you posted that?

 

where would it say on my truck what the size of my final drive gear is on my truck?

 

i did not write that someone has add to my post

 

if you look on your diff cover their is a tag get the number and post them someone will decode them

 

On the 8.8 axle the ratio is actually stamped on the tag in the lower left corner. It's kinda hard to read most of the time, but it's there. I don't know if the 9" is that way or not.

 

One other way to get a rough guessament would be to jack up the rear end both wheels off ground if it's a posi only one if it's open .. Make a mark on the drive shaft put tranny in neutral and spin tire one complete rev. count how many turn the drive shaft make. 3 1/2 turn makes it 3.50 Gears 4 plus a little more turns makes it 4.10.

ShaZam

 

Thanks guys, i'll check that tag and get back to you guys on those #'s so you can decode them. Maybe i'll even try your technique shazam, sounds interesting to me.

 

Hey guys, i finally got around to getting those numbers on the diff tag. Here is how they looked on the tag:

S838A

55 8 8 1D09

I'm pretty sure this is what they are but some of numbers were a little hard to read so correct me if i'm wrong.

 

You're missing the first number of the second line.

It's either 3L55 8 8 or 3 55 8 8

meaning a 3.55 trac-lok or 3.55 open respectively. Check the axle code on the vehicle ID sticker on the door jamb. "19" is 3.55 open "H9" is 3.55 trac-lok

 

What does "trac-lock" mean? If my engine is in pretty good condition what kind of gas mileage should i be getting with this gear? What other gear sizes are available for my truck and which would help my acceleration but still give me decent gas mileage? thanks guys.

 

limited slip.

The differential has a clutch pack so that if one wheel starts spinning real fast (no traction) the other gets some power too. These offer a lot more traction than an open diff. wish i had one

 

I figured it out, i have the open diff. Which gear would give me better acceleration but still give me decent gas mileage? i get crappy milage as it is already, like 12 or 13 in the city, and i don't want to take that below 10mpg.

 

instead of re gearing, you could just get 31" tires, that way if your tread is a bit old, you can sort of kill two birds with one stone.

the bigger tires will give you more grip, and also lower(or raise... whichever way you look at it) your final ratio. I have a 3.55 and 31" tires, it still accelerates pretty well for a pickup, and the highway is fine if you stick with the speed limit. She'll cruise at 70-75mph, but it requires a lot more pedal than a simple 60-65. it seems that 55mph is the sweet spot in OD.

 

im running a 88 f-150 XLT lariat 4X4 regular cab standard box with the 300 6. i bought the truck for 500 bucks after the previous owner ran it out of oil and ive run it about 2 years since and im overhauling it and getting it bored .030and was considering a performance cam to give it alittle more snuff...if i put a performance cam in it will i also need to adjust or replace the computer chip that controlls the timing? if anyone could help me out i would realy appreciate it. thanx