Here's a picture of the drain tube out of the '66 LTD.

This is about 21" in centreline length and molded with the odd angles of attachment.

This is the problem I am having in finding something that will work off the shelf.

I can't help but think that the rear ventilation system on the Ford 4 dr hdtop models was a last minute decision to add. Which in fumbling around for the cheapest way to make it work in production resulted in these oddball drain tubes.

Note: The 4 door hardtop wasn't produced in great numbers. For those who may not know what the rear drains are please allow me to explain. There is a rear vent assembly in on both sides of the rear glass that is vacuum operated. The outside cowl vent looks like the cowl vent in front of the windscreen. As a result there's a large gutter mounted underneath with gutter spouts in the trunk/boot area above the spare tyre.

So there are extremely thin (think inner tube material) rubber tubes that connect the gutter spouts to holes in the floor behind the rear seat. If these tubes rupture or clog up, water can enter the car during a rainstorm or carwash.

The rear drain on the '65-'66 4 door hardtop Fords is a sticky wicket indeed. Since there's no aftermarket part close enough to even sort of work with modification. I had to really give this one a think and start making the parts.

The original piece is a thin (think inner tube thin) piece of molded rubber with odd size ends and a piece of steel in the lower section (of which is pretty rotted away inside the rubber) that bolts to the section of floor just behind the rear seat.

Just a recap picture and here's the odd part.

It almost looks like a large intestine ---> EWW.....

Anyway, I have noticed a design flaw with this, in that at the end they had molded some kind of flapper at the drain end and all this did was hold in leaves and other bio matter that both of these were almost full off.

So whatever I came up with, it must be open so debris can pass through easily. This plugs up and water could pour into the back of the car in a good rain storm or car wash.

My initial idea was some kind of plastic molded part that mated to the floor with a gasket then have that open up to the same diameter as the gutter nipple above and a piece of aircraft ducting connecting the two.

So I knocked this up so far.

These bolt to the floor right behind the rear seat with a gasket The third base bit is a template to cut the cork gasket.

I ordered the aircraft grade 2.5" ducting and stainless hardware to put attach everything.

I still have to do post processing on these 3D printed parts in order to make them look more injection molded, but you get the idea.

For those wondering how one designs this, first you start with a 3D model you have to make on a CAD program. There are numerous free CAD programs out there and of course the ones you pay for.

This is the second attempt, estimated on the first go round and once it printed out was able to measure where it needed to be in the car and make the adjustments to come up with this one.

Once you have the 3D model you need to set it up in the CAM software. This is the software that translates the 3D object to the actual device making it. In this case I'm using Slicer for my 3D printer. This is where you set the object up on the platter (where it's to print) and adjust settings like brim/skirt, temperature, speed, hollow fill %. These change from 3D printer to 3D printer for best results. Much of it is trial and error.

Here it is almost finished. Our little 3D printer is a cheesy little kit, but it works well surprisingly.

The run from the bottom of the rear vent is not a straight run, actually it curves quite a bit probably the total curve is somewhere (estimating) 100-120 degrees of curve in the pipe. The aircraft ducting I picked is neoprene impregnated fiberglass, there are all kinds of materials to choose from. But it's flexible and sturdy and it with the water necks I have made angled miss the spare tyre.

I'll just use stainless clamps to affix the hose unto the gutter nipple and unto my water neck adapter.   Back to the rear drain dilemma, I believe I have put together the parts necessary to solve the lack of rear drain tubes in aftermarket.

I bought all stainless hardware so there's no need to worry about future corrosion for the fasteners.

I'm not totally sold on the ducting, but I haven't been able to find 2.5" rubber flexible hose. I have found coolant hose in 2.5" it really isn't all that flexible (without kinking) and it's still well over 20 dollars per foot.

This tubing is still several dollars per foot and seems to be the best fit for the time being. The neoprene rubber impregnated fiberglass core should last many many years.

So this part is done, when the underside is painted for the last time I can install this.