I have had the luck of having to cotnact both of these companies for various reasons. Engn Builder because the water pump I bought was fautly and 12voltguy because I melted one of the wires he sent me when I ordered my dual battery and dual winch incabe control. Both of these companies are great to deal with! Engn Builder responded early in the morning to me about the water pump and told me who to email to get a new one on the way. And by early I mean before 6 am pst. Now, don't get me wrong Engn Builders stuff is not short on quality. If you buy from them you'll be happy with their high quality engine parts. I just happened to get one that slipped buy QC. 12VoltGuy, he responded to me within 45 minutes of me sending him an email when I was confused about how to wire in my dual winches and battery. He helped me with my custom order and even worked really hard to get everything on to the ashtray switch panel I ordered from him and his work is also very high quality. I would buy from him in a heart beat again. But once again I wasn't paying any attention ad put the wire to close to the exhaust (my fault the wire doesn't work anymore) and I asked him how much a new cable would be, and not only did he go longer for me since my truck is an extended cab but he's sending it for free even though I told him it was my fault. All in all these are two companies that I would suggest that if you ever need high quality craftsmenship and engine parts and want good service if there's an issue to go to. They are awesome to deal with.
(If this is in the wrong section someone message me and I'll have the mods move it)
(If this is in the wrong section someone message me and I'll have the mods move it)