Used OEM Auto Parts: A Buyer's Guide

Your VIN (dashboard, driver's door jamb, or registration). It pins down the exact year, engine, trim and options, which is what decides whether a part fits.

OEM, aftermarket, or used OEM?

• New OEM: made by or for the vehicle's manufacturer, bought new from a dealer. Exact fit, highest price.
• Aftermarket: new parts made by other companies to fit many vehicles. Usually cheaper than new OEM; quality and fit vary by brand.
• Used OEM: the original factory part, removed from a donor vehicle. Factory fit and materials at a used price. Its condition depends on the donor car, which is why grading matters.

Used OEM makes the most sense for parts where factory fit matters and new prices are high: engines, transmissions, body panels, doors, lights, modules and interior pieces.

How interchange works

Manufacturers reuse the same parts across years and across "twin" models. A door from one year often fits several years of the same generation, and some parts are shared between badge-engineered models (for example, many Chevrolet and GMC trucks). That's called interchange.

• Mechanical parts (alternators, starters, pumps) usually interchange by engine, so match the engine size and code.
• Body parts (bumpers, grilles, lights, fenders) can change at a mid-generation facelift, even within one generation.
• Trim and options matter: sensor cut-outs, heated mirrors, fog-light holes and 2-door vs 4-door all change fit.

Our parts search widens a year/make/model search to the whole interchangeable generation and tells you when a year was a split year that needs a VIN check.

What the grades mean

Parts in the MR. STAC network are graded so you know what you're getting before you call:

• Grade A — Excellent: the best condition available for that part.
• Grade B — Good: normal wear for its age.
• Grade C — Fair: usable, with noticeable wear or cosmetic damage.
• Grade D — Core: sold mainly as a rebuildable core, not as a ready-to-install part.

What to check before you buy

• Engines: ask for the donor's mileage if it's known, and whether it was running when the car came in. Check for cracked blocks, sludge and missing sensors.
• Transmissions: match the exact transmission code and drive type (2WD/4WD/AWD); 4WD parts usually won't fit a 2WD car.
• Body panels and lights: match color (or plan to paint), check for hidden dents and broken mounting tabs, and confirm option cut-outs.
• Electronic modules: some need programming to your VIN after install, so ask your installer before you buy.
• Everything: ask what comes with the part (brackets, harness, sensors) and what the return terms are.

If the part isn't listed

Not everything gets listed online. Tell us what you need and we'll check yards across the network and call you back with what we find. Include your VIN for the best match.

Getting it installed

If you'd rather not install it yourself, you can book the install in the same call as the part.

Search every yard in the network, or call to hold a part.