After a couple years of abuse and use as a work vehicle and hauler with no seats, losing the rear bumper after a move was the last straw. I will was already missing a rear side widow, cracked windshield, busted mirrors, broken window switches, failed stereo, broken instrument cluster, cracked dash top, torn dirty carpet, ripped front seats, torn headliner, among other things. Upon getting the bumper, I ended up with everything I needed to make new again. Donor vehicle was exact same year but had the higher options, DVD and sliding power doors. My question is, can a harness be bought and put in to make the DVD player work or should I go back and pull all the wiring out of the donor? Can I just pull enough to tap in to the pre-existing wire in mine or will I have to change the entire harness of the van? Also, can I convert my doors to power sliding with equipment from donor?

I would recommend swapping over the 'better' harness. Do it now while everything is out.

Ok. It goes from ceiling to the floor and across the floor. Do I need everything over the dash and through it even into the firewall and around the engine?

I would just splice it in. Solder joints only.

So, how far do I pull and where?

I think you're saying that you see cables going in one side (of a run) and out the other. If they go in and out with the same colors then you could theoretically cut each side out then splice them into yours later.

It might be a good idea to verify them with a meter before cutting.

Well, what I'm trying to figure out is does the entire wiring of that van need to be taken or can I just go as far as I can reach at the dash and just clip. I need everything that'll run the DVD, vanity lights and possibly, sliding doors

Do I need anything under the hood or can I just clip at the fire wall?

Seriously, you are better off just transferring over the entire chassis harness. When you start cutting things, bad things happen. Then you'll be back in a month asking why such and such isn't working. Do it right the first time and be done with it.

Alright 👍