Yeah your gonna need new/used everything, if you get a used differential from ebay check to see if the spider gears are still there or send a message to the seller, how's the main ring gear and pinion?

Once you get everything out I'd check the housing for damage...like I said when I rebuild mine I got a used diff that still had the spider gears, I bought the master overhaul bearing kit to change out the carrier bearings on the diff, the pinion bearings and it came with all the shims.

Overall I think I spend a total of 250$ for the diff, bearing set and oil.

 

Ty I have maxed rep on you. You have been a big help. Ill keep this updated.

 

Not a problem at all, I hope it turns out good and you get it back up and running soon.

 

I would not go to ebay on this. Any junkyard will have lots of these. I got one in my garage. But I'm in the panhandle. You got to have some closer than that. Are you sure it's 355. Alot of them are 373. You may want to change. (I see big rubber) Of course you will have to change the front diff. But thats eazy on a TTB.

 

First I would be certain of the gear ratio. I haven't seen many 3.73 Bronco's though. Count the teeth on the ring and pinion then divide the gear teeth by the pinion teeth and that's your ratio.

Then get an axle from a local junkyard. Make sure it's the same style pinion. The older ones are flange and the newer ones use a yoke. You might have either one as Ford changed right around then.

 

Yes its a yoke, I will do that, plate on rear end reads. S838F 355 88 3J30. SO IM ASSUMING 1988 355 RATIO. Also did a search;
https://www.ford-trucks.com/forums/8...ear-ratio.html

 

If you're confident that the gear ratio hasn't been changed then go with that ratio. The 88 in the tag refers to the diameter of the ring gear (8.8") not the year.

 

It does very well with the 355 "granny" 1st (NP435 69-79 trucks swapped in with a 302)

 

agreed seems thats what im reading. I will count and divide when i pull apart, there is no saving this axle some searious scoring and ring gear has broken teeth

 

Yeah 39.5 12.50 16.5

 

Usually its stamped on the ring gear atleast on mine it was maybe because its an aftermarket?

Im wondering if thats why your rear end failed cause of that gear ratio with those tires?
Check this link out
Tire Gear Ratio Charts

This chart is basically saying you should have 4.88 gear ratio with those 39" tires

 

You're running 39" tires on this truck? No wonder the axle failed. You can't run tires that big on stock Dana 44 TTB and Ford 8.8" axles. They simply will not hold up to that kind of stress. Swap in another axle if you want but you'll be doing it again a year or two down the road.

You need some one-ton running gear.

 

Or downsize tires (cant believe i said that lol)

 

Yeah, I bought the truck honestly 2 weeks ago like that, but Im getting 37" military tires so i may just do swap to a better ratio. I have new 16.5 rims so i can get very nice military tires at $450 a set in Ga. with 90% tread. How would I go about with the front axle swap? It climbs like a boss in 2wd lol. its just a toy for me and my 2 boys

 

And honestly, It may not be that ratio I start out in 2nd gear no issues. Its not acting underpowered (302) and runs out fine. I will pull it apart and do the equation to determine ratio. Im just going by tag.