From Gineipaedia, the Legend of Galactic Heroes wiki
The ships appeared to use old technology. The ships had 5 engines arranged in a cruciform pattern at the rear, separated from the rest of the ship by a rearward flaring cone, of possible shielding from engine radiation and backwash. Each ship had 6 large spherical tanks, of presumably propellant. As additional power generation, each ship had 8 large and 2 small arrays of solar panels extending from the main body of the ship.
The ships used for the Exodus were enormous, capable of carrying 5,000 human beings with enough food production capabilities to feed at least that many people for decades. It is also fairly certain that each ship had limited production capabilities for other essentials as well as establishing an industrial base at their destination.
It is fairly probable that the ships of the Exodus Fleet were based on early, long-range colonization ships from the early days of Earth's push for the stars, as they appear remarkably similar in design to the first extrasolar space craft that attempted to reach the Centauri Starzone in the Alpha Centauri Expedition.