Factory build sheet

1981 Mazda RX-7

Build JM1FB331-B · Coupe

VIN positions 1 through 8 read JM1FB331 and position 10 reads B. Those nine characters define this build. Position 9 and positions 11 through 17 differ on every car.

Every RX-7 whose VIN starts JM1FB331 and carries B in position 10 left the plant with the same engine, transmission, drivetrain and equipment listed below. We know of 18 of them.

  • Decoded Jul 7, 2026
  • 18 known VINs

Factory specification

As filed by Mazda with NHTSA for this build. Fields the filing does not record are left out entirely — a missing row means no recorded value, not a missing feature.

Engine

Engine model
N2
Horsepower
91 hp
Fuel type
Gasoline

Body & chassis

Body class
Coupe
NHTSA body type
PASSENGER CAR
Doors
2
Manufacturer
MAZDA MOTOR CORPORATION

Weight rating

GVWR class
Class 1
GVWR
6,000 lb or less

Gross vehicle weight rating is the loaded ceiling set by the manufacturer, not the car's own weight.

The same build, other model years

Mazda used the VIN pattern JM1FB331 for 5 model years. Nothing but the year changes between these pages, so the price gap between them is depreciation on an identical car.

How this VIN pattern is read

A 17-character VIN carries two kinds of information: what was built, and which one it is. This page is the first kind — the nine highlighted positions.

Positions Characters What they encode
1–3 JM1 MAZDA MOTOR CORPORATION · World manufacturer identifier
4–8 FB331 Model, body style, engine and restraint system
9 × Check digit — computed per vehicle, not part of the build
10 B Model year — 1981
11 × Assembly plant
12–17 ×××××× Production sequence number, unique to each vehicle

18 vehicles carry this build

Every VIN we have decoded to JM1FB331-B shares the specification above.

  • 18 Known VINs

Keep going

Where this data comes from

Specification fields are decoded from the manufacturer's filings in the NHTSA vPIC database, keyed on VIN positions 1–8 and 10. We publish the filed values as they stand and leave out anything the filing does not record.

Vehicle counts come from the 18 VINs of this build we have seen in dealer inventory. They are a sample of the road population, not a production figure.