I'm new to Ford trucks and i am wondering what is the difference between 3.55 Limited Slip and 3.73 Limited Slip. I think my truck has a 3.31 with no limited slip.
The dealer i just bought the truck form will install LS for free if it doesn't have it. The axle code on the door is "27".

2000 F150 XLT 5.4L Supercab

 

Welcome to the site!!!

Try the link posted below. It has helped me to figure out what is on my truck, as I bought my truck used this last spring. Good luck.

Tiny


http://www.fordf150.net/howto/decode.php

 

Welcome ! 3.31s will get better mileage if your truck lived on a flat highway. 3.73s will have better performance/quickness and towing ability, while still having plenty of top-end speed. City mileage will be similar between the two. I would jump at the opportunity to get a free LS. To install a LS, the rear end will already be torn down to the point that a ring & pinion installation will be a minor addition. I would ask for a 3.73 LS or provide them with some aftermarket 4.10s and tell them to throw these in during the LS disassembly.

 

Thanks for the advice.

I think i understand that the higher the number the better towing ablility. ex. 4.10 better than 3.31 The lower the number the better gas mileage. If this is not correct please correct me.
The LS goes in Friday.
After driving this truck for a week i can understnad why it is the best selling vehicle in the US. The better traction form LS will only make it better.

 

How did you get the dealer to provide it for free??

You are one lucky guy!

 

I wanted a 4x4. He couldn't sell me one for what i wanted to pay. But he wanted to sell me a truck. He offered to have LS put on for free. He might not have known how much it would cost. I'm not even sure how much it costs, but i do know that it will be useful and not as good as 4 wheel drive but better than not having anything at all.

You know sometimes when you go into a dealership you may catch a salesperson at a weak time and they just want to sell something so they will make bad business decisions.

I think that is what happened.

 

Well, kinda....the 4.10s will get you quicker acceleration, increased towing ability, higher cruising rpms reducing highway mileage, and a lower top speed. The 3.31s won't help much for city mileage. Otherwise, they suck..... unless you remove your top speed limiter and go to the Bonneville Salt Flats.