At a Glance

> Brake Size Match: Confirm your brake assembly is 12.25" × 3.375" before ordering.
> Bolt Circle Check: Verify the 8-stud, 7.5" bolt circle configuration on your existing setup.
> Axle Date Matters: Dexter made major 9K and 10K GD component changes in 2009, so axle build date and part style should be checked carefully.
> Date Break Check: Confirm the axle was manufactured after July 2009.
> Old-Style Drum Check: Do not use this as an interchange for older 8-288, 8-232, or 8-256 series two-piece drums.
Brand: Unbranded
SKU: RP9-123-01

Before You Order

Match the part number, measurements and connection points that apply to your trailer.

Bearings	Match inner and outer bearing numbers.
Seal	Match the seal number or dimensions.
Bolt Pattern	Verify the complete lug pattern.
Brake Size	Confirm when applicable.

Product Details

Trailer Axle Brake Drum / 9K 10K GD 13G Applications

M-Parts Brake Drum for 10K GD & 13G Axles — 12.25" × 3.375" — RP9-123-01

M-Parts machined brake drum for compatible Dexter-style 9K, 10K General Duty, and 13G axle applications manufactured after July 2009. Designed for systems using 12.25" × 3.375" brake assemblies and an 8-stud, 7.5" bolt circle configuration.

Part Number: RP9-123-01 12.25" × 3.375" Brake Size Replaces Dexter 009-123-03

Overview

This M-Parts brake drum is a replacement drum for compatible 9K, 10K General Duty, and 13G axle brake systems built after the July 2009 component change. It is intended for trailer service where the axle, brake assembly size, bolt circle, and drum configuration match the listed specifications.

R&P Service Insight

Brake drums must match both the brake assembly size and the axle hub/brake system design. This drum is for the newer post-July 2009 Dexter-style configuration and should not be matched only by axle capacity.

Brake Size Match: Confirm your brake assembly is 12.25" × 3.375" before ordering.
Bolt Circle Check: Verify the 8-stud, 7.5" bolt circle configuration on your existing setup.
Axle Date Matters: Dexter made major 9K and 10K GD component changes in 2009, so axle build date and part style should be checked carefully.

R&P Knowledge Hub

Compatibility: Commonly used on 9K, 10K General Duty, and 13G axle applications manufactured after July 2009 where specifications match.

Vehicle / System Fit: Trailer axle brake drum applications using 12.25" × 3.375" brake assemblies and an 8-stud, 7.5" bolt circle configuration.

Installation Notes: Verify axle tag, brake size, bolt circle, drum design, and existing part number before installation.

Performance Insight: A correctly matched drum supports proper shoe contact, braking surface alignment, and service fit on compatible heavy-duty trailer brake systems.

Brand & Fitment Note

Selling Brand: M-Parts

Application Reference: Dexter names and part numbers in this listing are used for compatibility and application reference only where the listed specifications match.

What This Means: This listing is for an M-Parts brake drum, not a guaranteed Dexter OEM-branded item unless specifically stated and verified.

Before Ordering: Verify axle build date, axle tag, brake size, bolt circle, hub/drum style, and included components before installation.

R&P Repair Insight

Older Dexter 8-288, 8-232, and 8-256 series two-piece drum setups are not the same as this post-2009 drum style. Always compare your existing drum and axle information before ordering.

Date Break Check: Confirm the axle was manufactured after July 2009.
Old-Style Drum Check: Do not use this as an interchange for older 8-288, 8-232, or 8-256 series two-piece drums.
Parts Shown in Diagrams: This listing is for the brake drum only; related hub, brake, bearing, seal, stud, or hardware components are not included unless separately stated.

Features

Replacement for Dexter 009-123-03

Listed as a replacement brake drum for Dexter 009-123-03 applications where axle date, brake size, and drum configuration match.

Post-July 2009 Application

Used with newer 9K, 10K General Duty, and 13G axle brake systems manufactured after the 2009 component change.

12.25" × 3.375" Brake Size

Designed for compatible brake assemblies using a 12.25" brake diameter and 3.375" brake width.

8-Stud 7.5" Bolt Circle

Matches applications using an 8-stud configuration with a 7.5" bolt circle pattern.

Specifications

Specification	Detail
Part Number	RP9-123-01
Brand	M-Parts
Product Type	Brake drum
Application	Trailer axle brake drum replacement
Material / Finish	Machined brake drum; finish not specified
Brake Diameter	12.25"
Brake Width	3.375"
Bolt Circle	8-stud configuration, 7.5" bolt circle
Replaces Dexter	009-123-03

Fitment / Application

Category	Details
Vehicle / System	Heavy-duty trailer axle brake drum system
Primary Fit	Dexter-style 9K, 10K General Duty, and 13G axle applications manufactured after July 2009
Brake Assembly Match	12.25" × 3.375" brake assemblies
Notes	Older 8-288, 8-232, and 8-256 series two-piece drum setups will not interchange with this post-2009 drum. Verify axle tag, measurements, and existing drum configuration before ordering.

Included Components

Quantity	Item
1	M-Parts brake drum, part number RP9-123-01
Not included	Hub, brake assembly, bearings, seals, wheel studs, wheel nuts, mounting hardware, or other related components unless separately stated

Verify axle tag, axle build date, brake size, bolt circle, drum configuration, and included components before installation. Dexter names and part numbers are used as compatibility references only. This listing is for the brake drum only.

Shop More Brake Drums & Components

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M-Parts Brake Drum 10K & 13G Trailer Axle 12-1/4 x 3-3/8" After 2009 9-123 8-430 (RP9-123-01)