How to Read a GM Parts Diagram

A parts diagram looks intimidating, but it’s built on one simple idea: an assembly is drawn “exploded” — pulled apart along a line — so you can see every piece and how they stack together. Each piece gets a callout number, and that number is your key to the real part number.

The one thing to understand

The number printed next to a part in the diagram is not the GM part number. It’s a callout — a simple index (1, 2, 3…). Somewhere on the page there’s a list that pairs each callout number with the actual part number you order. Read the diagram to findwhich piece you need; read the list to get its part number.

Above: a made-up assembly (housing, cap, bolt) drawn exploded, with callouts 1–3. Every real diagram uses the same idea.

Reading the illustration above, a legend would pair each callout with a part number — for example:

Callout 1: Housing — example part no. 00000001
Callout 2: Cap — example part no. 00000002
Callout 3: Bolt — example part no. 00000003

(Those numbers are placeholders for the illustration — a real legend lists the genuine GM part numbers.)

How to use it for real

Open the specific part on the retailer’s page — the diagram there is the accurate, current one for your vehicle.
Find your component in the exploded view and read its callout number.
Match that callout to the part number in the accompanying list.
Confirm it fits your build with your VIN before ordering.

We deliberately don’t reproduce GM’s or a retailer’s actual diagrams here — those are copyrighted. Instead, view the real, up-to-date diagram on the product page for the exact part you need (for example, on any GM part page we link out from).