Wanted to throw this out there and see what other's think. My code on the door panel for the axle reads H9. H9 code indicates the rear differential should be a 3.55 Limited Slip. Now, this is a 92 Ford F150, 4x4, E4OD, and 5.8 EFI engine. I really believe that the original rear differential may have been removed. This is why I think this. At 55mph, the rpms are 1600. I could be wrong, but I would've thought that 3.55's would turn more rpms at this speed. The wheels are 31's. Also, one back wheel will spin by itself in the back. Would not both wheels spin with limited slip? What do you guys think? Thanks.

 

1600 rpm could be a result of the E4OD as it has a good OD gear. Also with the one wheel spin, if the truck has a lot of miles, the locker could be worn out and need of a rebuild. The way you can tell is on the back cover of the rear there should be a tag, if it still a 3.55 locker, it should say 3L55 and some other numbers. Take a look and see if its there, good luck!

 

H9 is 3.55LS I turn about 2000rpm at 60mph... so that seems about right. The overdrive on my 5 speed is .79.

 

Wow, What RPM's do you run at 70? Im at 2 grand at 72 MPH... Bout 1700 at 60, 1400-1500 at 55

 

About 2500 rpm at 70mph.

 

you have a manual but is that when your in OD?

 

Thats some high R's, my truck SUCKS the gas anything over 2 grand.

 

I turn about the same with a AOD and a 5.0L

 

There is something wrong with that man. it shouldn't be that high

 

Yeah my truck likes the gas and yes that is in 5th (OD)...and I still want 4.10's.

 

I installed the tach from another cluster maybe I screwed up but I don't think so. I'm going to double check those figures tomorrow on the way to work.

 

oh ok that may make some sense

 

lol i didnt want to be the bear of bad news lol. Even tho its a manual i would think it should be around 2 still, if not i wouldnt want that gas bill.....

 

My 1990 5.8 has 3.55 gears and when it did have an E40D I was running right were you are. also with 31x10.50s.

now with my 5 speed I am running 2400 at 70 and 1500 at 45. 5th gear is a .84.

 

my 90 E40D had a .68 OD.