The Tru Trac is fine. It is a helical gear unit. There are no clutches,so that makes perfect sense. The Detroit Locker can use synthetic also,being a coupler style diffferential. I just don't and won't put synthetics in a clutch unit,or something that requires friction to work. If it wears out prematurely or fails,you won't likely look at the unit,but the person who built the rear. It's just like when an engine fails. A lot of people will ask "who built it?"
in all reality fluid should not make any rear blow up or fail quickly. usually is will be a noise issue and the way parts work with each other - the fluid helps make everyone play nice together. your POSI will still work in the steel clutch Eaton and Auburn metal cone units... once the parts get worn in and mate well they will tend to stick like a plastic cup stacked in another plastic cup - super suction and more twist force will have over come. When the units side gears do release it is violent and then tends to stick again when the axle twist is released and will be repeated over and over till the turn is completed. This is what is causing that annoy rap shutter, rap shutter, rap shutter around corners. Some people are not bother by noise as much as other are.... If you are use to open non posi vehicle it can probably get on your nerves... Most muscle cars are clunky, noisy, air leaking, loud exhaust, ticking solid lift motored vehicles from the factory anyway...lol. try to enjoy the cars they were imperfect from the get go so... God help us, we love them anyway. Jim J D
