The rear end is gear oil is one of the few fluids that isn't all that critical, provided you stay right there in the 80W-90 and 85W-90 range. Most any API GL-5/MIL-2105-E SAE 90 Hypoid Gear Oil is going to fall into that range. You just don't want to go below 75W (viscosity at cold temps) or above the 90 (viscosity at 100 °C (212 °F). Particularly, stay away from the things like 70W-140. Reduced axle durability will result if you stray outside of that range. Any good quality GL5 rated XX-90 weight gear oil is going to be fine.
MB 235.0 and 235.6 is the spec.
I generally use the Fuchs Titan Supergear 80W-90 oil from Europarts, or I just use the Mopar oil (which is also the same Fuchs Titan oil, incidentally). My local Dodge dealer carries it in stock, as it's used on several Chrysler vehicles. I've also used Mobilube S 80W-90.
The power steering fluid should probably be changed at least every 5 years because of degradation. It's hygroscopic like brake fluid and will break down as it absorbs moisture. It's not as critical as brake fluid, which is supposed to be changed every 2 years, but I've only changed mine once at 5 years. I should probably have it changed again. But as for the power steering, I've had mine flushed and refilled twice, and I've had a couple of small leaks (loose hose clamp) that required adding additional fluid. All it takes is for the steering fluid level to be about 3 caps full of fluid too low for the steering to stutter and shudder when backing out of a parking space or turning the steering when while parked.
The history of discussions of the right and proper power steering fluid to use is long and tedious. The 2003 service manual (same steering parts as the later models) specifically states Mopar ATF+4. The 2004 manual, for the same exact parts, states synthetic ATF III and nothing else or else! The 2005 manual states Mobile ATF-D. And a snotload of real world experience says most any ATF or PS fluid will work. Lucas Power Steering Stop Leak is also popular for small leaks, with no detriment.
Both times I had mine changed out I used the genuine MB power steering fluid or the Mopar stuff, which is the same as the MB fluid. The genuine, real-deal stuff is a clear yellow, which turns gray when degraded. ATF is red. That might be important if you use color as an indicator. I carry with me some Shell ATF 134 and use that in the power steering if I I'm low on fluid.
