Complex sentence: Two built as Model 450-1-1 and 450-2-2 respectively, (46-065 and 46-066); powered by six Allison J-35-GE-7 turbojet engines for the first flights.
Split into simpler sentences: Two built as Model 450-1-1 and 450-2-2 respectively, (46-065 and 46-066). Powered by six Allison J-35-GE-7 turbojet engines for the first flights.