Spark plug gap

[SoCalSlaughter]

I have a 1990 Chevy Suburban 5.7 Ive been trying to find what the gap is for the plugs. I read online its .35, .45, .50. Im not sure which is true. Dont have the emissions sticker under the hood anymore. On a side note, I wanted to check the plug gap (Which was .46 on all plugs) I kept getting a code 42. Which is the est line shorted or grounded. Ive tested the ignition control module and swapped it out, checked the set timing connector and it still pops up. Usally if Im at a stop light for a few minutes. Thanks!!