78 – 84 Rainey Street will probably be the name of a nine-story office and retail development that will soon occupy the current food truck park. Sackman Enterprises, also the developer of 70 Rainey, and designer, Sixthriver Architects, are involved with the project, which was to begin in 2018, but has not.
Unless things change, an underground section will have three levels of parking with a total of 99 parking spaces. The design has human-scaled bungalows at the front of the building which reflect the rhythm of the street and the character of the original homes on Rainey.
Here's a link to Towers.net for more info: https://austin.towers.net/rainey-streets-9-story-mixed-use-project-moves-forward/
Here's a rendering from the Architect.