I just finished putting my d450 headers in my 66 Barracuda. They were a pain but they are in now so I hope they do not leak anywhere. What they do not tell you in any of the ads is what the directions say that come with the headers. Yes you do have to lift the engine, they say about 4 inches. They also say to remove the right angle oil filter adaptor if you are using one which i did and the passenger side went in fairly easy. Oh, they also tell you to cut the flanges that go between the tubes against the headers. They ship them attached but you have to cut them to get the slip tubes apart. Now the drivers side was the fun one. I was putting my engine in after having the car redone so I did not have the z-bar in at first. I did lift the engine but they say you can get the lower part of the header around the torsion bar with a little muscle. That part was the easy part anyway.The middle tubes have 2 flanges which are a huge pain, one of the bolts you have to put in before trying to put the top of the tube down to attach it to the bottom of the flange. I am not necessarily recommending this but we ended up welding 3 of the 4 bolts in the top part of the middle tubes so that you did not have to play with them when trying to get the nuts started from the bottom of the car. We then put the starter in and the z-bar. The outer tubes go in okay then. A couple of the bolts into the head are also very tedious as you cannot get a good wrench fit so it took a long time to tighten the bolts. I know this is long but you have to be very patient. My brother and I worked for about 4-5 hours on the drivers side to finally get it in. We did have to dent the header slightly to clear the steering linkage, I also have no PS. We did this after the header was in and checked it out. We also had to slightly rework the brake lines to the master cylinder and the proportioning valve. I do have the ceramic coating and it did get scratched in a few places so I will have to see what that means when I have driven the car a bit. Oh, the slide areas are not ceramic coated and they tell you to put a Copper sealent in them. We kind of figured that they will rust together after a short while anyway. Just an aside, we also thought that if we ever did this again we might cut the flange that goes between the header tubes along the head as it would free up a little around the spark plugs.
I hope this helps.
