Called on my friend Brian this morning: he says his Clansman are PRC-320 which use slug-tuned and switched inductors for antenna tuning.
By comparison the PRC-321 has an external ATU known as the TURF which he thinks does not use a roller-coaster, but the 321 also has an external tuner known as the SURF or
Selector Unit RF. Brian has not had one of these but the pictures show that they probably had a roller-coaster.
If you can give more details or a photo, I expect someone can advise further.