Finished harpooning both tanks the other day. Because I didn't feel like running all over town looking for fittings I used what I could find at the local farm supply store. 3/4" brass barbed "L" fitting into the tank and 3/4" brass barbed/threaded straight into the filler neck.
Overall the job wasn't too difficult, especially on the front tank. I had found replacement grommets at Advance Auto that fit the hole in the tank and accepted the 3/4" fitting. Had to soften the grommet in the sun before it could be worked into the hole in the tank. Insert the barbed L and run 3/4 fuel hose up to the filler.
Gutting the filler hose wasn't too hard. It comes out of the truck easily and the work can be done in a vise. Only takes about 10 minutes. Drilled and tapped a hole in the side of the filler tube and screwed in the fitting and brazed it in place.
Same process for the rear tank except that dropping the tank is a bit of a pain. I am glad i did it though because I ended up having to cut all the mounting hardware for the spare tire. I never would have been able to get the spare off along side of the road-the parts were so rusted! o I replaced all that stuff and coated liberally with anti sieze compound. Will be checking that once or twice a year from now on!
Anyway, got the spare off and dropped the tank some of the way down. Receiver hitch was in the way to a degree, but the tank came down far enough to get the job done. I ran my hose above the top tank strap and checked it after raising the tank back into position. Appears to be plenty of clearance for the hose with the tank installed.
Results:
Mixed, in my opinion. Even with full tank venting, it is possible to shoot fuel back out the filler. It will take a little bit of practice to make it work as efficiently as possible. I run both tanks to nearly empty each time so I can check mileage with every fillup, so I have a good idea of how much fuel each will take. I can very rapidly (with the "big truck" filler) throw about 14-15 gallons in, tapering the flow down as I approach 15 gallons. Then can fill the rest of the way at a slow, steady rate. It still is much faster than before, but it is easy to shoot fuel back at you when filling, especially with that rear tank since the filler enters the tank in the side of the tank rather than down through the top, like on the front tank.
I followed the basic instructions from Steve Baz'z site:
http://pages.prodigy.net/stevebaz/index.html

Overall, worthwhile, but maybe not the perfect solution. I'd like to hear from someone who installed the Transfer Flow system to compare results.

Also, since I began the work (which took several days working on and off and running to my school shop to do the brazing) I have been getting a fuel filter warning light from time to time. On the front tank, I ran it for several days with the relief hose simply suspended in the air until I could get the fitting brazed into the filler tube. That is when I first noticed the problem. But it seemed to go away until I drew fuel out of the modified rear tank on my way home from a long trip the other day and it reappeared. It was odd: the fuel filter light would come on at decelleration and go away as soon as I hit the accellerator. But after a while, it flip-flopped and would come on upon accelleration and go off when I let up.
I am wondering if, by completely sealing the tanks I have created negative pressure as they empty fooling the computer/sensor into thinking that the fuel filter is restricted? I did notice for the first time ever that when I opened the fill cap, it hissed. I wll have to investigate this further, but any thought you all might have would be appreciated.

 

I wanna know where all the debri went that you drilled outta the filler neck and tank top.

Cowboy Steve

 

Well, I didn't drill the tank top at all. I reached up there with an WD40'd damp rag and wiped the area down before I even pulled the original anti-rollover valve and the grommet. Then carefully wiped around the grommet hole in the tank using a motion moving away from the hole. Could something have gotten in there? I guess, but I was deliberately careful not to let that happen.
As far as the filler work, that was all done at the workbench and then the filler was washed out in the parts washer after drilling, tapping, and brazing the fitting in.
I'll probably throw another filter in, but I just changed it the first time that light started flashing. Those filters look like they are fairly high capacity and they are a little $alty too.
Someone had suggested from a previous post that there may be a sensor having fits. I'll probably look at that this afternoon when the shade moves over the driveway.

 

I must have missed the part were you said you pulled the filler neck. If you just put a new filter in and the lights still comin on and off it probably is the sensor goin bad. Good luck

Cowboy Steve