Hey guys... Looks like I found a sweet deal on a 99 Mk4 jetta that I'm going to pick up.

I read up and searched how to take out the factory HU, which shouldnt be a problem, but, I havent found out where I can find the correct wiring harness for a double din radio (factory harness to after market). Any ideas where I can find one?
Also, isnt there a "K-Line" or something that I have to be mindful of or else I'll get a CEL?
I know that as the case for my old MK3.

BTW, feel free to make recommendations on a nice double din radio