Terry, the builder changed air intake setup so finding OEM may be a problem. Caterpillar
Air intake hose is a thick rubber rib tube. Having air intake restrictions such as your talking
about with your 400 hp engine can suck the air filter into engine under restrictions starting
If intake blockage get severe. Removing air intake tube to engine area open different doors of problems, shortens life of filter. You should notice exhaust smoke excessive and not clearing
out driving down the road with air restrictions to your engine. I can get technical information
for your C-9 air intake the way engine built and tested and provide that to you on Ask Dave
Technical Information. Dave Atherton Retired Cat Mechanic