I just checked, actually it is your write-up that I've had permanently open in my browser as a reference. My plan is to add the 4th wire, I've got everything ordered and tools in hand, just waiting for the rest of the bits and pieces to show up. In the tank, I'll delete the combined ground and add a separate ground for the fuel gauge, and use the open hole in the 4 pin connector in the tank that connects to the bulkhead connector. I could make that wire, but I think it ended up being cheaper to buy a harness kit for the Fleetwood from a parts store. O'reillys had it, good price and I'll just rob the ground wire I need from it. It would've cost more to buy a small spool of teflon/ptfe wire, and it wouldn't match the factory black w/ white stripe. The brand was Precision and according to the label it was actually made in the usa, so that 's a win.
On the outside, the 4 pin connector from the Racetronix harness is a Metri-pack 150.2 flat 4-way, and the 4th terminal is simply not there, it was plugged with a little plastic rod which can be pulled out. I've got Metri-pack 150 series female terminals on the way and a small spool of txl wire, black with a white stripe to match the factory stuff and I'll populate the open spot on that connector. I'll do continuity checks through everything to make sure pins are going where I think they should be, and I'll need to double check that the wires are in the same order on the B-body as the D-body, but if not I'll be de-pinning everything anyways to swap connectors and can reconnect them in the correct orientation if needed.
After that it goes to a Weather-pack flat 3-way, which I'll be replacing with a Weather-pack flat 4-way, those connectors and terminals are also on the way. On the hot wire upgrade harness, there's another set of Weather-pack flat 3-ways, which I'll also probably switch out with Weather-pack flat 4-ways. At least I think that'll be the easiest. I could maybe go another way and keep one set of 3-ways, and run the additional ground separately but that might just get messy. Once I get into it though I'll figure out what looks and works the best. And I'll get some pics so I can do a detailed write-up if anyone else ever runs into this and wants to mod it to work on a Fleetwood.
The only thing I wish I had done was order the wagon version of the hotwire upgrade for the extra length. I didn't even know Racetronix offered that, but it is on their website. I found it while searching other threads for solutions to the Fleetwood thing. Being the D-body is longer I may need to extend that wire, but that is the least of my problems in this whole mess. And I certainly don't dislike the Racetronix products, the quality is very good. It's just their lack of communication, nearly a full week has passed since I contacted them and still no response whatsoever. And I don't like how they've mouthed off to others on here when complaints were brought up.
Also, I too considered seeing if Gary would be interested in duplicating the Racetronix harnesses and adding them to his lineup, including a Fleetwood version. It'd be perfectly easy for him to make them, and at this point I have every single component identified save for a couple that I don't need to mess with. The bulkhead connector is one example, I don't know specifically how to identify or find a source for those, but I haven't tried because I don't need to mess with it. I suspect it's easy to track down though. Then you could use whatever pump you want, factory, aftermarket, high-performance, etc, just get the harnesses from him, and get the pump of your choice. May need to have a couple different connectors to the pump itself available since they're not all the same.
There's only one weird anomaly I've come across, all the wire is supposed to 14awg, except I think a heavier wire for the hot wire upgrade up to the battery/alternator, but the short harness between the bulkhead and the vehicle harness is no way 14awg. It's definitely smaller, but that might be a limitation of the 150 series Metri-pack connectors, you're not supposed to put a larger wire into the terminals, I think 16awg is the max rated size, or maybe only 18awg, I'd have to double check my info on those. Unless he went with a solid wire there to handle more current but keep the size down?
I haven't de-pinned that harness yet so I'm not sure, but the wire seems awful tiny to me and seems to defeat the point of everything else being 14awg or bigger. And yet even the in-tank harness does have 14awg wire, and the connector at the bottom of the bulkhead connector is using 150 series terminals and he managed to cram the larger wires for the +12v and ground to the pump onto those. It's just weird, I'll have spare 150 terminals since they come in pkgs of... I think 10 is the smallest qty, so I could get some more txl wire and redo that harness while I'm at it. It just seems silly to have 14awg everywhere, but then bottleneck the wire to the pump right before entering the tank, and then go back to 14awg inside the tank.
Your points about the pump failure issues cause me some concern. I could've sworn that I had seen posts about them failing a couple years ago when I first started making up my list of support mods I wanted to do before attempting to get serious power out of the motor, but I couldn't find them when I recently received my kit and discovered the purple pump in it. Makes me wonder if I should save myself the headache now and just order a Walbro while everything is apart and out and while I'm waiting for other stuff to show up. The pump by itself isn't terrible price wise, but by the time I get done with this I'm going to have a lot more than the original $200-ish into this upgrade.
Last thing of note, I was pleased to discover that I was able to get a new fuel tank seal. There's a parts dealer in town that primarily supplies the dealers and mechanics in the area, but they have a counter inside and a person can go in and buy whatever they want. You can get most of the same parts that the dealer has, but without the dealer markup. I got a genuine ACDelco seal (last one they had on hand), Made in Canada, and was about $7. They also even sell some stuff on ebay, but they whack on you on the shipping.
That's enough of my rambling on for now, and I added a pic of my present "nightmare". Hopefully next week I'll have this wrapped up and the car running again.