From what I gather looking at different posts:

1 - The quality of the 2021 led bulbs could be trash, why are you so fixed on getting them?

2 - You can’t just take led bulbs and put in halogen housing of older models, wont work properly.

3 - The 2021 led housing could retrofit in older models, but again see number 1. We don’t know if it’ll fit yet too.

4 - Wiring harness? If I know anything about 4runners is these things, as long as same generation, are so so similar. Probably won’t require a harness if retro compatible. Idk if 2021 is considered Gen 6 but based on the features that would be insulting to the 4runner, it’s a 5 Gen imo. Unless Toyota has officially stated its Gen 6. There’s almost nothing new.


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