Frank wanted the 70's because they were a heavier built engine than the 190's. He told me if he had a 70, he could get 25 years out of the running gear before an overhaul was needed. When he bought the 190 and 192, the 70's were not for sale.
Frank had a deal set up with Dollywood at one point to trade the 190 for their 70, but the Robbins brothers, who owned Tweetsie, didn't want to trade. Frank was not happy.