155.370 seems to be a pretty common interagency frequency across the nation. I, too, have heard local SOs using 155.370 in a repeatered fashion. It seems to be a popular thing to do in some areas between Abilene and San Antonio.
155.475 is called "DPS USA" around here. They use it to coordinate their meal activities and discuss marital issues most of the time. It is a pretty busy channel.
The 155.505 CLE is pretty active here. They do a lot of narcotics and Auto Theft Task Force sting operations on it. You usually hear them on channel 5, which is the talk around. When they get out of range they will switch to channel 6, which is the repeater. I know this because I hear them all the time saying stuff to the effect of "You're scratchy on channel 5, turn to channel 6." There may not be a CLE repeater in every town, just like there is not a narcotics repeater (159.090/154.935) in every town.
Regarding License and Weights, aka Commercial Vehicle Enforcement. Around here, we are in region 5, which means that CVE units are 56xx. It may be different in your region.
Here is Texas DPS unit designators in a nutshell:
Most units are 4 digits. The first digit is the region that they are in, 5 for West Texas, 2 for Houston area etc.
The second digit is kind of a subdivision of the first digit, or the region, and tells what regional office you report to. For example, 51xx and 53xx units report to the Lubbock regional office, while 50xx and 52xx units report to the Amarillo regional office. There are also 56xx units which are CVE and report to the Lubbock office, and 58xx which are CVE and report to the Amarillo regional office. Also note that all 51xx units report to the 5110 sergeant and all 531x units report the 5310 sergeant.
The third digit is another level of subdivision that describes your "patrol area" and what sub-regional (drivers license) office you report to. For example, 511x and 531x report to the Lubbock office directly, 512x and 532x report to the Plainview office, and 515x and 535x units report to the Levelland office. These "sub offices" are generally drivers licenses offices in smaller towns and do not have communications centers. If the third digit of your unit number is a 0 then you are some sort of higher-up like a corporal or lieutenant, etc. 5100 is in charge of all region 5A (Lubbock area) operations, etc.
The fourth digit is just a random digit that you are assigned. The only special one is xxx0, which is that particular section's sergeant.
There are also many special unit numbers which do not fit in the above mold:
1xx: Aviation unit. These are non-regional and report directly to the Director.
7xxx: Victims assistance
RNxx where N is your region: Radio techs. R502 is a region 5 tech, etc. Radio techs will also fill in for dispatchers occasionally, so I assuming they have at least a TCLEOSE Basic Telecommunicator certification.
90xx: CLE people like Auto Theft Task Force, Narcotics, etc
90Rx where R is your region: Drivers License people
4Axx: Rangers. I am still uncertain how their designators work; they could be 5Bxx, or any other combination, also.
KRxx where R is your region: K9 units
There are also a bunch of civilians in the 9xxx and 7xxx ranges. I have also recently heard some callsigns like "950" and other three-digit combinations. I am unsure what these are. Pretty much everyone in DPS has a radio callsign; both sworn and civilians.
If anyone has any more info I'd love to hear it.
Jeff