I've been searching through the forum looking for someone who's done this before but can't find anything about this particular mod. There's quite a few posts about changing gear ratios but not about changing open diff to LS diff.

I have a 2001 F150 Supercrew, 5.4L with axle code 19 (3.55 open). I pull a 23' boat with it and have noticed that on the launch ramps it's difficult to keep the wheels from spinning. Instead of buying a 4x4 (which adds cost and maintenance and reduces fuel economy) I'd like to convert my 3.55 open (code 19) to a 3.55 limited slip (code H9).

Has anyone converted an open diff to limited slip and, if so, what would I need to do?

The other alternative is to buy a complete B6 axle (3.73 LS) and swap them out but those seem to be hard to find.

 

Youll have to replace the differential, Get a Detroit truetrac.

 

It would prolly be easier / cheaper to buy an h9 or a b6 drum to drum from a junk yard or Craigslist vs trying to change the differential.

 

Ok. I found someone on CL selling a disc-to-disc V941A (code H9) from an '02 F150 4x4. The tag on the axle notes a 3L55 (3.55 Limited Slip), 9.75" ring gear. Would this bolt-in to my truck? I also understand (by reading this forum) that the Truetrac is much better than the OEM trac-loc but as I'm on a budget I'm looking for a cheaper way to get LS diff can I bolt in the 4x4 axle with 3.55 gears and expect everything to match up to my 2x4 truck?

 

I think you mean 9.75 ring gear? They only put 7.5s in mustangs and rangers I believe. And if you get a used axle chances are its going to have a lot of miles on it and you'll just end up having to replace the trac loc soon anyways since they use clutch packs and wear out. You'd be better off doing it right and paying somebody to install a new differential for you. It will be a lot more reliable. Guess it depends on if you want good quality or "easy and cheap"

 

Correct you are - that was a typo on my part. I meant 9.75" not 7.5"
You're right about the miles though - might just be better off paying the $$ to have the gears swapped by a pro (since I don't have the tools needed to correctly lash them) and add the Truetrac during the same job.

 

do you have a 9.75 now or a 8.8?

 

I will double check when I get home but I think it's a 9.75, code 19. There is a possibility that it's 8.8, code 18 but I'll look in the next few hours and post back.

 

You can install what is called a lunch box locker alot cheaper than replacing the whole rear diff. You have to swap out the spider gears and install the locker. If your paying more than $400 dollarsfor a complete diff I would look into some other form of limited slip.

 

Ya was just going to say it might be better to just swap in a 9.75 if you don't have it, there pretty beefy axles for a 1/2 ton and is definitely worth upgrading to if you want to buy a new one anyways