Ok to start off, after doing some research I concluded the engine in my 1968 F600 was a 391 (The 391 Was Put In after original over heated, its a 1965 model engine), but after digging deeper I've noticed every 391 mentioned here is a Four Barrel Carb, Mine is 2 Barrel is it still a 391? Did any 391's come with Two Barrel Carbs? Also, my distributor (Not original to engine) has three vacuum lines, one is vacuum advance, what are the other two, and where do they go?

 

Engine code is the 4th digit of the VIN, post what it is.

Most F600's came with the 330 2V Medium Duty FT engine.

The 330 2V Heavy Duty, 361 2V & 391 4V were extra cost options.