Complex sentence: The 47J was a four-seat variant of the earlier three-seat Bell 47H, the 47H was a deluxe variant of the 47G with a fully clad fuselage and enclosed cabin.
Split into simpler sentences: The 47J was a four-seat variant of the earlier three-seat Bell 47H. The 47H was a deluxe variant of the 47G with a fully clad fuselage and an enclosed cabin.