Tech: 88-89 GMT400 Quad Sealed Beam upgrades (Bosch T84 E-code headlights)
I’ll start this thread off by simply stating that the output of the 88-89 sealed beam headlights are a joke. This thread will outline the OEM lighting in the quad headlight trucks, and available upgrade options. Many people simply say switch to composite headlights; while this is a valid option...
![www.gmt400.com](https://www.gmt400.com/data/styles/12/styles/gmt400/xenforo/icon_192.png)
88GMCtruck has all the details in his thread above