What is the vacuum hose size for a 1993 Chevy 4.3?

There isn't one single vacuum hose size for a 1993 Chevy 4.3L. The engine uses multiple vacuum hoses of varying diameters. You'll need to consult a repair manual specific to your 1993 Chevy 4.3L (the exact model of the vehicle is important, as even within the same engine size, variations exist) to determine the correct size for each hose.

Trying to guess based on generic information could lead to vacuum leaks and poor engine performance. A repair manual (Chilton, Haynes, or a factory service manual) will have diagrams showing the vacuum routing and specifying the size of each hose. Alternatively, you can take a damaged hose to an auto parts store; they can usually match it to the correct size.