The District 6 service patrols are now operating on the system. They seem to spin a wheel to decide which talkgroups they're going to use. I have noted the various trucks talking to the TCC on the following:
11686 D6 Traffic Control Center 1 11687 D6 Traffic Control Center 2 11688 D6 Traffic Control Center 3 11689 D6 Traffic Control Center 4 11690 D6 Traffic Control Center 5 11904 D6 Tow
For a time, I thought it may have been a specific talkgroup dedicated to a specific highway in the area. But, nope.
As far as the specific site, that's a tough one. The radios at the traffic control center typically affiliate to 1.75 or 1.148. The trucks will bounce from site to site as they're on the road. The I-76 and I-95 patrols should normally affiliate with the two Philly towers (1.83, 1.91). But, they could also hit the two Willow Grove sites (1.81, 1.82), too, depending on where they are.