I made mine. Took 2 pieces of 4 inch clothes dryer vent, split each one up one side (and then had to trim some off each one to make them fit together) Fiddled with them a bit to make them fit together and taped with some air duct tape. It's not perfect but it works and it didn't cost a fortune. I know it sounds confusing, but I don't know how else to explain it.
2014 JKU Rubi, red, no mods..... yet
1979 CJ7 AMC 360*T150 3 speed/Dana 20*Moser 1 piece axles*Edlebrock intake manifold/carb*Cooper Stt 35x12.50x15 tires* Black Keystone Wheels*MSD cap, rotor, wires*Rusty's HD Tie Rod and Drag link* Goferit tie rod reversal* Borgeson steering shaft* Sams HD steering box bracket*Tire Carrier Bumper*Skyjacker Nitro N8000 shocks*Mountain Offroad Heavy duty 4 inch shackles* 12,000 lb Badlands Winch with wireless remote*
1980 CJ5, AMC 304
1988 YJ, 258