I've built 4 flatties..2 with Ardun Heads the other stock. All of mine have 4 hoses..just like they had 1:1
Of course I know these kits are from Revell and less than 5 years old!
Top motor has the ardun heads..look next to the fan belt even with the motor mount(same on other side)
Upper hoses fit to the front of both heads.(middle pic)
Lower motor is from the Revell 32 kit, has lower hoses and mid mount top hoses (not shown here)