Sorry to be so long replying, I'm out of town...
Anyway, I've seen the double clamps more than once. One is on the truck that I pulled my donor out of, I have it and it is in the line pic. That was an 87 Chevy TBI. I remember seeing it on at least one other. It was notable because I had never seen a clamp like that anywhere else. Those clamps are actually 1 piece, joined under the worm/screws with 2 separate slotted belts. Never seen a double clamp before I started looking for tanks. Most of the other tanks with rubber hose type senders were already loose or stripped, but they were definitely factory GM with in-tank pumps. The pic I posted clearly shows the sending unit with the wires built in. The tank is on the ground. If you want more (better) pics or part numbers or anything, PM me and I’ll get what I can when I get home.
As for the lines, the rubber lines go from the hard line on the frame to the tank sender. Those hard lines I cobbled together to have a temp tank setup to move my truck while I'm working on the body. It is definitely not stock. /forums/images/icons/laugh.gif BTW, the clamps in the tank pic are just cheap worm clamps. The only odd-ball (one piece) clamp I have is the one that is on the other pic that you referenced (that’s the only reason my temp lines were shown). The rubber line and bolts are there just to keep the lines clean while the tank is off. The rubber line that is used to actually hook it up is rather expensive EFI rated rubber line from NAPA. Other than jumping from the frame mounted hard lines to the tank, all other connections in my fuel system are metric o-ring.
It’s late, I hope that makes some sense. Unfortunately I have no manual for 87, I just figured that was how the early units were done since I saw it on more than one of the tanks. Maybe I’m confused or something. I also apologize for taking this further off topic but, like you Dorian, I’m now curious about the reality of something I had thought I knew. Your questions don’t bother me at all, I may have made assumptions or misunderstood what I saw. Wouldn’t be the first time. Maybe some (all?) of these were electric pumps for carbs or something? I don’t know… Has anyone else EVER seen a TBI sender that used rubber lines to jump to the frame hard lines? If so, what was it on?
I guess all I *know* for sure is that I have in my tank a GM sender, with an electric fuel pump, and rubber hose nipples. It worked with my TBI and I replaced it with a new TBI pump by asking for a TBI pump from an 87 K10 (the donor). I also *know* I saw that on a couple of different GM tanks with fuel pumps in the tank, that includes rear center tanks like Blazer/Suburban tanks. However, the vast majority were threaded o-ring fittings. Oh well…