How to Identify a Car Part (OEM vs Aftermarket vs Reproduction)
Updated July 27, 2026 · By the makers of Car Identifier: AI Spotter
A box of parts at a swap meet, a mystery component in a project car, a "genuine" part on a marketplace listing: knowing what a part actually is decides what it is worth and whether it fits.
Three questions identify any part: what is it, what does it fit, and who made it (OEM, aftermarket, or reproduction). Here is how to answer them.
Read the part itself
- Casting and part numbers: molded or stamped codes are the strongest evidence; manufacturers keep number formats consistent for decades
- Logos and foundry marks: OEM parts carry the maker's mark or the automaker's logo, often in hidden spots
- Finish and material: OEM castings are typically cleaner with consistent machining; cheap repros show rough seams and soft detail
- Date codes: many components (glass, electrics, rubber) carry date stamps that should match the car's production window
OEM vs aftermarket vs reproduction
OEM means made by or for the automaker: correct fit, collector value on classics. Aftermarket means a third-party replacement or upgrade: fine for function, usually worth less to collectors. Reproduction means a new copy of an obsolete original: it keeps old cars alive, but selling one as an original is where buyers get burned.
On collectible parts (muscle-car intake manifolds, JDM wheels, vintage badges) the OEM-vs-repro question can be a 10x price difference, so it is worth five minutes of checking.
Photo identification for parts
AI part identification reads the shape, markings, and finish from a photo and estimates what the part is, which vehicles it fits, its likely origin (OEM, aftermarket, reproduction), and a value range. It is the fast first screen: it will not replace decoding a casting number for a high-value purchase, but it instantly tells you whether the number is worth decoding.
Before you pay collector money
For expensive parts, verify: cross-check the casting number in a marque forum or parts catalog, compare weight against a known original if possible, and be suspicious of aged patina in the wrong places. Sellers rarely fake wear where real wear happens.
Scan the part with Car Identifier
- Switch to part identifier mode.
- Photograph the part with its markings visible.
- Read the identification: what it is, what it fits, OEM vs aftermarket vs reproduction, and estimated value.
- Save it with a note (price, seller, location) so swap-meet decisions get easier.