Here is a link for some more usefull info for Muddy Peak includeing Images, GPS, Map etc.
The access road is now (January 2011) in much worse condition than described in the Approach Section here. We encountered a couple of 4wd and many high clearance places even before we reached the Quarry area. There are several sections of the road that are badly washed out. The wash leading to the metal sign and the end of the road is also very bad, we only managed to get to within about 1/2 mile of it even with 4WD vehicle. Very sporting approach.
In December of 2016, it was not possible with a Subaru to even enter the wash at the start of the foothills. It's a jeep and truck road only now.