What do you call auto parts that are meant to fit specific vehicles and those that aren't?

Solution 1:

Most parts have applications to several vehicles because the manufacturer

• Used the same part for several years of the same vehicle
• Used the same engine/component in multiple models
• Borrowed technology or used the same supplier as another manufacturer

There are many cases where a part was only used on one make/model/year of a vehicle and the manufacturer used something else the next year.

Aftermarket suppliers often find where two "OE" (Original Equipment) parts are identical or close enough to identical to combine the applications and offer a single part.

Last, there are cases like exhaust where a Direct Fit muffler that matches a specific vehicle is offered whereas a generic muffler that fits a large number of vehicles will also work but might need some custom welding or pipes upon installation.

Solution 2:

I typically think of parts that are not meant for a specific model or models of vehicles to be "universal" or "universal fit" parts. I can't say where exactly I picked that up though...