[bilfman]

The low and hi of the 203 function basically like an 'open differential' function. The T case allows slippage between the front and rear diff, kind of the way spider gears work in an open diff, this just helps with drivetrain strain because these were fulltime units, really helped with stress when operating on dry pavement. Hi loc and low loc make the case function like the 205 and such. When in the 'loc' the t case does not allow any slippage between the front and rear diff, just functions like most other cases.

That said the 203 is as tough as a 205, the case weighs about 360 lbs and the chain is twice the size of a 208. Many peeps convert to locking hubs and will put in a part time kit, the part time kits is basically a modified shaft for the rear of the case. The problem with this mod and many find out the hard way. Is that the 203 is meant to be spun to oil the top of the case. A part time mod does not allow the case to spin and oil. There are 2 ways to assist this. Run the unit in 4wd either engage the shifter or the hubs about every 200 miles for about 10 minutes. Or as I am trying now (but I've been assured it works) put an extend the filler plug 2 inches higher with some 1/2 pipe, this lets you fill the case 2 inches higher and will oil the top end. Remember this case is oiled with a max 30 weight oil. DO NOT use gear oil. I have used a 10/40 for years with no problems, but being from Canada the lower viscosity helps in winter.