Shown here is the PRT "power recovery turbine" on the Wright 3350.

Not real sure of the date, but I think it was a November 30, 1992 issue of FLAGSHIP NEWS that mentioned the donation of a Curtis-Wright R3350/TC18 DC-7 engine which was restored by the members of GOLDEN WINGS, an association of American’s Professional Flight Engineers. Marsh Stern started the project by raising $35,000 through donations from American’s active and retired flight engineers. The restoration was managed by Don Williams and Jim Connaughton, a Phoenix based line mechanic. Because none of American’s original DC-7Bs had survived, the organization bought a similar engine from a later Sabena Airlines DC-7C and they modified it to DC-7B standards. The last of American’s 58 DC-7s, relegated to freighter service, was retired in 1966. In case you were wondering the DC-7 could fly up to 90 passengers coast-to-coast in about 8 hours.