Did this on my truck, 89 f250, and now it fills up great. Here's what i used, 2 hose barbs, 1/2in pipe on one end, and1/2 barb on the other, 2 90 deg. hose barbs,1/2 pipe and 1/2 barb,4 hose clamps, 8ft. 1/2 heater hose, FOUR 1/2in. conduit nuts, and JB WELD. Did front tank first, it's the easiest,reach up on top of tank and remove the tank vent,take the vent valve just removed,and take all of the insides out of it,next,i drilled it out to 5/8in.,take a 90deg. hose barb and file down the threads,so that it fits in the vent snugly,once you've done that remove it and apply JB WELD and install it back,now the vent is finished move on to the filler neck and remove it.On the right side of filler neck,there is a dimple,drill a hole there 5/8in,insert a straight hose barb in the hole,with a conduit nut on the inside and outside of the filler neck,you may have to file the hole some to screw in the barb fitting,on the nut on the inside of the filler neck,just run it down even with the end of the hose barb,apply JB WELD to the threads on the outside of filler neck,then run down conduit nut on outside and tighten snug,apply JB WELD over nut and remaining threads.Let JB WELD set overnight,next day,put hose on barb on vent,and clamp it,install vent back in top of tank.Reinstall filler neck on truck,now connect the 1/2in. hose to the filler neck.IMPORTANT MAKE SURE HOSE RUNS DOWNHILL TO TANK NO SAGGING,OR YOU WILL CREATE A TRAP AND IT WILL NOT VENT.I used some zip ties to secure,front tank is now done. Back tank is same procedure,except for you have to lower the tank to get to the vent. Hope this helps some others,sorry about the way it's written up,computers aren't my thing,better at wrenching.