The people who work for the vendors are NOT the people who wrote the catalogs, who used to work there, I suspect. The presumption that whomever you talk to on the phone knows cars, and the one you have, can be incorrect also. Realize, too, that THEY are looking at the same catalog YOU are looking at, so they have no insights or similar to add to the situation.
At THIS point in time and forward, always presume the customer service rep has no personal knowledge of what you are seeking to get parts for, period. All of the people "who might have known something" have retired or are getting ready to, I suspect. Just the reality as I see it, BUT there can be exceptions to that, too. When you might encounter somebody who seems to know something, and you find out they DO know something, continue to patronize them, but always carefully until you build a good working relationship with them over time. Always ask for them if you need any help or other parts, too. It MIGHT be that everybody there "knows something" (which is great to find), but do NOT presume they are all working from a "community knowledge" situation of sorts. Allow them to prove it to you, respectfully.
As for weatherstrips, they should have some cross-sectional illustrations in the back of their catalog which can be compared to what is on your car. Especially if they also sell "roll goods", which is what the rear deck weatherstrip is sold as, just that they pre-cut it to length rather than by the foot.
This issue is NOT only in the Mopar hobby, by observation. Almost everybody has Chevy parts, but some of those Chevy parts will also fit other GM cars of a particular platform. Ask them if their parts (mechanical or weatherstrip) will also fit a similar Buick, they'll automatically say "No", although the casting number on the part is clearly the same on the Buick as their Chevy part has. In reality, this particular example can be variable, so if THEIR catalog says it does not, it does not. FWIW
So, look for the same part at different vendors' online catalogs. You might discover that what one place has, another one does too, which means one might be the actual producer of the part and the others are just re-selling it (after buying it from the other vendor or the same producer). IF you can determine whom the main producer is, that's where you might find the most aware employees. Asking the rep where they get the part can result in variable results, too.
Sometimes, you can get a good idea of "what's out there" from the online catalogs at
www.rockauto.com. Otherwise, some of the better restoration vendors' websites, too, even if what they say they sell might not be for your specific vehicle.
Just my experiences and observations,
CBODY67