You’ll have to supply more info than that...or ask the seller what they mean by “long range tanks”.
There are several methods to add fuel capacity to a 170: Javelin tank on the floor of the bag compartment, 175 wing tanks, or Flint tip tanks, and maybe others.
I’ll add a cautionary note: It sounds as if an eager buyer might be charging into a prospective purchase fairly uninformed about the airplane being offered. This can be a very expensive way to seek an airplane to buy. Getting a “specification” sheet, photos, and doing an online search of FAA database might be a better way to start out. Most aircraft maintenance records of modifications can be obtained online with or without the seller’s permission.
