The rear end on my 79 F150 SuperCab Ranger 4x4 with a 351M and C6 trans recently blew out. Had a bearing freeze (yes there was oil in it) and came apart and chewed everything up. That one was a Ford 9 inch, geared in 4.11 as I understand it. Axle code on the door says H9A. The tag on the rear end says:

FE-AX-8LD, then the second line has: 9 and 365A

There's no tag on my front axle, so I don't know what it is. This is part of my problem. How can I find out without pulling it apart?


I've been hunting around all the yards around here for weeks and finally found 1 (used to see em all the time!) ford 9 inch. There was no tag on it and the axle tag on the doorframe was gone. It came off a 79 F150 4x4 with a 351M. It has 35 teeth on the ring gear and 10 on the pinion, whereas my old one had 37. Does that make a 3.5:1? The only stamped numbers I could find on the ring gear are:

C6AW-4205-B (although the 5 may be a 6. kinda worn)
MCCP39 (9 may be an 8, again worn)

What I need to know is what the rear end gearing is, and what the liklihood is that I can use that rear end with the front when I have it in 4. Part of my problem is I just lost my job and don't have a lotta funds to work with, and I need to get my truck running. I appreciate any help. Thanks guys

 

if i had to guess id say your old diff was a 3.73 and the one you found is a 3.55. my suggestion? get the rear end you found. take the front end too, and swap the gears. itll help your fuel mileage too.

 

If you don't mind my asking why do you think the old one was a 3.73? I looked through the axle codes in the Haynes manual ( I know, probably not the most accurate) and the H9 stands for 4.11 in 79. Not sure what the "A" stands for though.

I've already pulled the other one and have it here. Problem is that I don't have the $ to buy the front one. I am on the back end of broke right now. can I put in the replacement one, and use my 4 wheel without blowing something out?

 

As long as your spinning tires you would be fine (mud hole or something) but if you lock it in on blacktop youll have problems

 

i figure the old one because it is 37 toothed. unless the pinion has only nine teeth. then it IS a 4.11. you CAN use your fourwheel, but only in mud and on snow and ice. and expect the **** end to be makin a valiant effort to pass the front. in other words, i would NOT use the fourwheel till you can change the front.

 

How complicated is it to change the front gears when I get to it? Is it just a matter of pulling the front axles and then pulling the gears? Or is it better to pull the whole axle housing with the gears still in it? The only time I use 4 wheel around here is when its snowing or I stumble across an irrisistable mud puddle. Is it going to be an issue in these conditions? They aren't too frequent by the way.

How will running a 3.55 going to affect general 2 wheel drive driving? I live in the mountains- lots of hills.

 

just gotta pull the axles and swap em. not too much more involved that the rear, to my knowledge. runnin 3.55s will make your crawl speed a little faster, but its nothin four low cant overcome. im not sure what the gearin is in my 76, but its pretty dang high in my opinion, and it has no problem luggin around at idle in 2hi. and it doesnt even like to idle... lol.

 

H9 = Ford 9" limited slip rear axle, 4.11 ratio.

The front axle tag can be found while scrapping dirt off the pumpkin cover that are vertical with the tubes. You also can go by BOM on the tube itself.