Gas tanks are different on my two bikes and fuel vac line ng

[what]

Ok I've had an 85 454 LTD for about 2 years . It's no longer running don't know
So I picked up an 84 the other day and we'll the tanks are different one has 2 vac line ports one on either side
The other not both have same carbs and I'm pretty sure I know but I need some input as why. And what to do

[eaglerider]

The tank with the two "vacum" lines (actually vents" are likely California models....and there is no 84 454LTD...first year model is 1985

[joenson]

If it’s an ´84, I’m pretty sure it´s a 440 LTD - which is a different bike.