Unfortunately, except for the "named" (Theodore and Karl) gun battalions and batteries, there is no way to tell merely from looking at the CR listing. So, if you want to sift out the 210mm Howitzer battalions, you will have to do a bit of tedious rooting about, looking at the TOE for the individual battalions, and then shifting them upward to higher level HQs. I like to send them to OKH whenever possible, because once there, they can be pulled to any subordinate HQ on the map.
The 210mm Howitzer battalions are the M18 battalions, as shown in the screenshot below. If you have a subordinate HQ selected, you can choose to assign from the higher level HQ where you have the guns parked, and then select the particular type gun for the job. Likewise, the named guns will appear distinctively, so you can easily select them.
< Message edited by JAMiAM -- 11/2/2011 5:21:32 AM >