I've got an open diff on my 90' 2wd f150 and i want to switch to limited slip so i can be a little more off-road worthy. anybody got any suggestions? should i do a conversion or should i look in a salvage yard? whats the code for the limited slip diff?

 

Whatever the code is on yours, ex 19 for 3.55 open, the LS would be with a letter in front instead of a number, ex H9 355 LS.

 

The cheapest way to do this is to go find a traction lok differential in a junk yard, and just swap it in place of you open unit. Ford rear axles come with a tag on one of the cover bolts that has the ratio and will indicate if it is a traction lock. The bottom row of info, usually partially obscured with the bolt should read 3L55 for a 355 traction lock, whereas a 355 would be a 355 open. Check yours and it should be that way. I looked at one in a yard Sunday on an 02 Fx4 wreck and it read 3 L 55.

This does require setting up the gears, but only left-right and preload, no pinion shimming needed. Mustang guys do this alot for toys/race cars, with the hammer it in and out technique. I have a homemade case spread tool and enough measuring stuff to get by, but it is tedious. If you are lucky, you can get buy with the bearings from the salvage unit and th shims from your original, or the salvage shims.

You could use a new traction lock, they are only $250 or so new. Probably need about $100 in bearings and shims for the install.

Or have a shop do it!

The easiest way is to find a whole rear with the gear ratio you want and a
Traction Lok already installed, and just swap housings. Takes a half day.

There are a couple of limited slip units that will go into the existing open diff, but I have not tried them.