Hello:
I am appealing again to y'all knowledgeable people here.
I have only had my F-350 for 10 days and already got stuck this morning!!!
I had the two right wheels spinning while the two left wheels were just stationary on firm ground. I definetly need limited slip diff.
I used to have a 94 F-250 with a ford 10.25 differential. I kept the core so I have that and I was wondering if I can use it in my 1999 F-350, but I have no idea if they are compatible, I have a 12 bolt differential the tag has no information (only says 74-140W synthetic oil only), there is a sticker on the casing, right next to the leaf spring that says 406C, and the axle code on the door sticker is 41. Obviously I have a 3.73 gear ratio, but can I use my old limited slip here?
Also, I am worried about rpm, to go 70 mph, I have the engine at about 2200 rpm. My old ford had 3.55 gear ratio and felt it could move a mountain. Is there a way I can put 3.55, 3.33 or 3.42 gears in my F-350 to save some diesel and engine wear?
Last, where can I find a list of the greasing points? I am going to grease it and want to make sure I am not missing any, I want long, reliable service from this ford.
Thank you very much and I hope everybody is having a great weekend.
Cheers
Dro

 

The only greese fittings are on the steering linkage. Unless someone replaced the front ball joints. As far as fitting your limited slip I don't know..

 

Hello:
Thank you for your reply.
I found out I have a Dana 50 in the front, and a Sterling/Ford 10.5" in the back.
I understand the Dana 50 is a 30 spline, can I put a a Dana 60 core with 30 spline or it won't fit?
As for the back, is the ring diameter the only difference with the old fords? Or I could use my 10.25" limited slip core?
Thanks,
Alejandro

 

Never heard of putting in a dana 60 my guess is no!
Go to drivetrain specialists site or randys ring and pinion or reider racing and look at the applications see if they are the same for those years.

 

You can't convert a Dana 50 to a 60. They look the same from the outside but the inside of the housing is different and won't allow you to install a 60 carrier and ring and pinion. 50 is a 30 spline with 1.5" inner shafts that taper down to 1.31" at the splines.

The 10.25" and 10.5" rears use the same carrier......all aftermarket part numbers are the same from '85 ( I think) on. So you should be able to use the LS out of your 10.25" in the 10.5".

You can change the gear ratio in both axles if you want as long as the ratio you want is available for both the 50 and 10.5". Bigger tires would lower the rpms somewhat......depending on what most of your driving was can't say what it would do for fuel mileage though.


Hope this helps.

 

Dear 99f350sd and DCSpecial, thank you very much for your replies.
I am happy I can use my old LS carrier, anybody knows were I can find a diagram of how it is put together so I can pull it appart and clean it?
My Chilton repair manual forgot to mention this part.
I hope everybody is having a great weekend.
Dro