as far I can tell, the 2007+ Expy doesn't have a Limited Slip available.

I'm going with 4.30 gears because I do at least 90% city driving. The Expy is a pretty good vehicle...but it is 6,000+ lbs. 4.30 will help me be a bit happier since it will give it some pep at all the stoplights I live around.
plus, the 4.30 gears will be slightly offset by the 33" tires I am going to replace my POS Pirelli STR's with


As for the Limited Slip decision...well I've already had 1-tire fire a few times with my current 3.73 Open carrier. 4.30 would be much worse. Mine is a 4x2, so I'm already at a traction disadvantage.

 

From the old days, a 4.10 gear does not necessarily mean less mileage. A lower gear helps get the mass moving much better for town driving-----HOWEVER-- that only works if you keep your foot out of the loud pedal. Unfortunately that is the hook, it is usually so much fun that you cant keep your foot out. As long as you are honest with yourself (I have had to try to do that) and realize your mileage may well go down. From what you are saying, the TC does not eliminate the single tire smoker, even on these heavy things. To me that speaks volumns about this 6 speed and its low gear gearing. I have no problem with going to 4:30 gears, but have to wonder the necessity given a mustang trailered w/trailer (unless its a fully covered and outfitted racing trailer) should only go ~5000 #. Whatever blows your skirt up----- .

 

Nope you can get the limited slip in the expy to this day but it had to have the LIMO package. You can order the diff from ford parts and install it. I'm not a fan of LSDs. My F-150 left me hanging many times when one wheel was on hard pack and the other was in muck. I'd go locker but worry about the CV shafts with that kind of torque going to them.

 

I know this thread is getting "long of tooth" but I am still interested in the affect on TC or RSC with a traction adder (LS/Locker/etc). I think Tylus is still watching, given his plans. I have been doing some "surfin" last coupla days and am about to form an opinion about that issue.

The Auburn site states that they are compatible with all ABS and electronic controls. I thought I saw the same statement for the Trutrac (eaton-detroit), but dam----darned if I can find it again! I have pretty well ruled out all clutch types (traclock/eaton etc). Had a traclock in my 460 van (D 61) and discovered that the clutches will wear out just running down the road. Seems that slightly different tire sizes on the rear (almost unavoidable) will cause the clutches to slip and wear out.

Apparently the smoothest is the trutrack, but because of torque biasing, does not give 100% lockup, however sufficient for almost all but Rock-crawling. Probably the same for the Zexel/Torsen, but not as much biasing as the Trutrack. The Auburn cone style apparently does uncouple the axles when normal , which I like, but may require some slight braking to get lockup. I have not been able to determine if the Trutrack does any uncoupling or just locks tighter to the unloaded axle when needed.

Anyway, given the "uncoupling" factor, which I like for this type vehicle, the Auburn (HD series) becomes my choice. BTW, I know about the cone wear and rebuildable issue. I kinda like the "Powertrax" , but some chacteristics dont appeal to me for this vehicle-----the 93 Bronco would be O.K.

I also had a very interesting experience with the 03 Gran Marquis after replacing the axle bearings in it this week, it has TC. After replacing bearings and refilling with new oil, I left the tires off, still on jackstands, and cranked the engine so that I could put it in gear and get some good low-speed circulation of the new oil. Darndest chattering and jerking you ever saw! My first thought was Oh S***! what did I screw up . It also would not go much above high idle in that condition. I saw the TC activation light on the dash lit, so I de-activated the TC with the dash switch and it quit all the chattering. Apparently one axle was turning faster (apparent slipping) and TC activated to clamp it. Good news is that for the first time (I think) the TC was activated---and worked. Anyway, just a little something else to read-------

 

I have a 2012 F150, 15000 miles, the "check acutrac" has come up on my dash when starting the truck. it happenned 5 or 6 times over a month or so in September. I would switch the screen back to fuel economy and the notification would go away. This notification hasnt come up now for the past month. I took the truck into a dealer, they tell me it needs some steering parts, the cost of the repair is $1700.00. There is mo problem with steering, braking at all, only this notification that occasionally pops up. What should i do?