who has the best e body under dash harness

Hello, looks like I might have to replace the whole under dash harness. Who makes the best after market harness? Year one the best? Also on their site it says some add ons maybe needed. What does the standard harness already have? Thanks

Pretty much only have one choice. That's the M&H harness sold through year one.

Accessory harnesses are for A/C, etc.

Thanks, are they decent quality?

They are the best on the market.
What part number harness are you looking at, I may be able to find a chart that tells you what the connections are. The main harness does not include any of the additional harnesses that plug into it.