Transorb was a modified Rho-class shuttle which had been upgraded discreetly by the Rebel Alliance to meet the Rebellion's demanding specifications for use in the Galactic Civil War. Sometime after the modifications were made it came under attack by two TIE/LN starfighters whom managed to damage the hyperdrive, though the group of Rebels on board managed to destroy these two fighters before the other four TIEs could reach them and jumped into hyperspace, arriving at the planet Muugrah. When they arrived they discovered the damage to the hyperdrive and so landed on the planet to get spare parts from Squarn's Junkyard to repair the ship. While there, the group discovered the R2-series astromech droid R2-D6 who helped with the repairs. The Rebels then flew the ship to a nearby Rebel base to download Deesix's memory.
Sources
"Buried Treasure" — Challenge 67 (First mentioned) (Unlicensed)
