Why does eBay Motors compatibility info omit large numbers of compatible vehicles?

[outyourbackdoor]

Is eBay Motors compatibility info customizable by the sellers? 

I recently found a car part that omitted a huge number of vehicles. It makes me nervous. 

My specific situation is I'm looking for a Ford/Mercury minivan transmission. If I search by any of the minivan models I find hardly any transmissions. But the SAME transmission was also used in many Ford/Mercury SEDANS. So if I search by the OEM part number I find many, many options. And if I search official OEM info online I can easily confirm that all these vehicles used the same transmission. But eBay says it's incompatible! 

Even more specifically, the Taurus/Sable transmission is the same as the Freestar/Monterey. But eBay doesn't show them being compatible. 

The specific part number is 4F50N or AX4N. (Those two numbers are used interchangeably by the companies.) This is a very long-running transmission used in many vehicles for many years. Yet if you search just by the minivans you won't find many available. ?

It's a transmission that was used in approximately 6 vehicles for 10 years, but eBay lists it as only fitting 2 vehicles over a short timeframe. So I am confused!

Where does eBay get this info? How is it revised or input?

Thanks for any insights.

[hebertsusedautoparts]

I am pretty sure eBay uses the Hollander interchange which is what almost all salvage yards go by and yes the transmissions have the same model number they are very different.

The AX4N is the case, the internals,valve bodies and electrical plugs and often gear ratio sets are different so even though the part number for the case is the same the unit as an assembly is not the same and more and more as modules and computers talk with each other it becomes more critical.

If you used a 2005 Taurus for example  you have a few options based on column or floor shift and overhead valve or dual overhead cam engine.

they are all 4F50N, AX4N's  they are not plug and play, Just for the linkage alone you would need to drop the valve body to change it for column if it was a floor shift version. Try getting a customer to do that.

It used to be so much simpler in the old days when a turbo 350 fit every Chevy and all you needed was to know short tail shaft or long.  

[bestdealinparts]

No, eBay has nothing to do with the compatibility chart. The info is added by the sellers. Chances are that when selling hundreds of unique parts, as a seller you may not be aware that a part was used in 10 different vehicles, so they set the compatibility to just one or two makes/models.

Also, sharing from experience, many times sellers are fully aware a certain part can fit multiple makes/models, but choose not to list those options because sometimes small changes may be needed to make the part fit, and buyers are not aware or have no idea how to do it, resulting in return requests for "defective", which is false.

Many times we even mention "DO NOT BUY if so and so...  because it will not work as an upgrade, it's not a plug & play item etc.", and the buyers would still purchase and use it for the circumstance we have specifically mentioned it will not work in, then we end up with aggravated customers though it was not even our fault.

Maybe this will help you understand why you won't see a complete compatibility chart like at the dealer's.