Per a separate thread, I am putting 2001 Park Avenue 3.8L back together following intake manifold replacement, etc, so I will recap success when completed in the other thread. But meanwhile I have encountered a few concerns in the assembly.
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Fuel rail connectors:
Fuel rail connectors are now leaking. Fuel system not pressured up yet, but daytime heat is expanding fuel in lines and the original connectors at the rail are now leaky. The 3/8" rear connector is dribbling badly and the 5/16" front connector is staying damp.
Per a search on this site I found several owners have had specialty connectors adapted for use. A few have mentioned Dorman part 800059 available at several sources, but this is for the 3/8" line only. Have not yet found any listing for a 5/16" size. Are these Dorman connectors holding up?
Since the search threads are getting dated, is there any newer suggestions for replacement connectors for both size lines? I can buy online or pickup local if Advance or Autozone can obtain, but first contact locally found no info unless I can supply a manufacture and part number. Not too keen on driving to a distant Buick dealer nor grabbing the JB Weld.
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Heater hose connectors at the tensioner:
When taking this apart, the oring seal hose adapters were set in place from heat and time. In putting this back together I now see the small retaining bolts have a thick shoulder and do not really tighten down against the ear, so only the orings provide seal -- the hose is free to wiggle about until time and heat prevent movement. Question is whether there were ever a grommet/spacer taking up the slack to hold it tighter in place?

Appreciate any tips you can send my way on these concerns. I am trying to get this project wound up, but many other things have dragged this out for longer than expected.

I would most likey say all you need to do is replace the FUEL O Rings
there is only one small O ring in each line
You can use a pick to get out the old ones
This is a cause of most engine fires because no one ever replaces them
The heater hose connections yes they float and you can move then back and forth
when the system pressurizes they move out against the head of the shoulder bolt
I don't understand the idea in it but ask GM right?
your really better off just replacing the fuel line O rings
as if you notice the plastic lines are like heated to fit on the metal lines
The replacement onces are plastic but getting them to seal on the metal line can
be quite a challenge

Regal Guy,
Thank you. The confirmation on the water connectors 'float' clears that question. I expect I may be looking for new Orings for those also as they feel a little 'too loose' after re-assembly.
The fuel connector Orings may prove more difficult to insert/replace. I assume Buna-N composition would be required. Not yet found a listing for these Orings separately so I may indeed have to go to GM parts dept -- very out of the way to me. Since it MUST be repaired or replaced, I will pick out the Oring in the very leaky 3/8" connector and try to figure how a new one would be inserted properly. I have now read several posts mentioning how difficult it is to seal junctions with replacement/repair style fuel lines.
It is these type supposedly minor but necessary project pauses that have drawn out this project longer than expected -- example it will be a couple of days before I can break free to go to big-town. But I should now have vehicle back on road early next week.
Again, I appreciate the information and assistance.

You can get the O rings from Auto Zone or other auto part stores 3/8 and 5/16 in a pack made by dorman dont forget to do all 3 for like 4 bucks

Regal Guy,
Thank you for staying involved in this.. most helpful. Quote "dont forget to do all 3" Unquote.

Three? I picked out one each Oring from 3/8" and one from 5/16" 90º connectors. One each (total two) is all I saw. There is a third plastic line running to the front of engine that "seems" to be a vacuum line via a valve that connects to the fuel pressure regulator. Did not see any Oring in that connector. Slips on/off very easy. Where is the third Oring you mentioned above? Will try the nearest AutoZone before noon tomorrow. Do you have a part number for that Dorman pack?

yes that one is the 3 one
Dorman OE Solutions - Fuel Line O-Ring Kit

Part Number: 800-013

Line: DOR
limited lifetime warranty
• UPC: 19495025641
•Viton
•2 Each - 5/16" and 3/8"

Bless you! That is very useful information! I will go to AutoZone in morning and obtain or order that package. Still do not see an o-ring inside that 3rd connector, but will explore that more tomorrow. Again I thank you for being so helpful.

If they don't have one in stock O'Reilly Auto Parts should
the O rings are just kind of deep in there so be sure to have a pic
to fish them out