these 80s engines are a disaster when it comes to vacuums hoses, theres tons of them and they go everywhere and one will be different from the next, its a mess, there is a label underhood soemwhere or on air cleaner that shows vacuum hoses, its the emissions label, youre supposed to leave it intact just for this reason, check for it under there, if not then youll have to find as close to year make model and engine as yours and copy off it, also 350 would not be a 5 or 10 series truck in 84, less its a 20 or 30 seriesa
good luck