Just for a little history ; of the Largest Caterpillar Pipelayers , or Sidebooms.
1. Cat 594 Built 1966-'75, 385 hp, 200K lift capacity
2. Cat 594H , 1975-'86, 410 hp, 200K lift cap.
3. Cat 589, 1986-'06, 420 hp, 230K lift cap.
4. Cat 591, 1989 (one only), 520 hp, 350K lift...