Robert is right. You do NOT have a Dana 35, even though several catalogs and even the Haynes manual mistakenly identify it as such. It is variously described as a Dana35 IFS, a Dana135, and mistakenly as a Dana35. It is a sort of hybrid Sterling-Dana35 model produced in Ford's Sterling VanDyke plant.
I have just order a Powertrax NoSlip unit that member go off road successfully installed in his 2001 Ranger, and Powertrax lists it as fitting a "Dana35IFS".
Both Ray Lobato (in California) and I (in Texas) tried to have limited slips and/or lockers installed over a year ago, but when the techs actually opened up our units, they learned that they were not Dana35's. I tried to have a TracLoc installed since their catalog lists a unit that will fit, but TracLoc was wrong. I forgot what Ray tried to have installed but it was also supposed to fit and it didn't either. There are about four companies that list an LSD or locker for our vehicles, but they are all wrong, with the possible exception of this new Powertrax that go off road has successfully installed. I will try installing mine sometime within the next month.