Wouldn't say they were real common in over-the-road trucks, but they were out there. Kingsway up in Canada ran them for many years:
http://www.hankstruckpictures.com/kingsway.htm
I think Texaco and/or Mobil used them to pull tankers as well. Regardless, I think a lot of the V-12 powered trucks ended up as fire apparatus, where large gasoline engines were favored over diesels until the 70's.