This is actually B-17G 44-83872. After construction, it was transferred new to the US Navy which modified it to a PB-1W airborne early warning a/c with BuNo 77235. Retired from the USN in 1955 and sold to the civilian market where it was used as an aerial survey a/c. Sold to the CAF in 1967 and initially marked as a B-17 from the 305th BG, as seen here.