This brochure shows first-generation Weber Genesis models Junior/1/2/3/4/5 and Genesis Perma-Mount (a natural gas model 5 on a mounting base). Note the black control knobs on models Junior/1/2/3 and gray control knobs on model 4/5/Perma-Mount. Those black knobs didn't stay around for long and were eventually replaced with gray knobs.
The earliest Genesis grills were first introduced in 1985 and had wide wooden slats on the work surfaces, as shown in this Genesis advertisement.
Note the array of Weber Torches shown on pages 2-3.
1990 Weber Genesis Gas Grill Brochure
Thanks to Jon Tofte for sharing this brochure!