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Marshall 9220 Hall Effect Speedometer Sender — main product image
Marshall

Marshall 9220 Hall Effect Speedometer Sender

★★★★★4.3 (54 reviews)

Drop-in Hall effect sender converts your GM/Mopar mechanical speedo output to clean 16-pulse electronic signal — no fabrication required.

$34.99*$48.95Save 28%
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*Price sourced from Amazon.com. Last updated:Jul 14, 2026.Price and availability are subject to change.

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Overview

The Marshall 9220 is a Hall effect speedometer sender designed to bridge the gap between older mechanical-drive transmissions and modern electronic speedometer heads. It threads into the speedometer port on GM and Mopar transmissions — TH350, TH400, 700R4, A727, and similar units — replacing the mechanical cable drive with a clean 16-pulse-per-revolution electronic signal. This is a common requirement on restomod builds, street rods, and any classic vehicle being upgraded from a mechanical needle gauge to an electronic dash or GPS-augmented speedometer system.

Construction is straightforward and purpose-built: the Hall effect sensor reads the rotation of the transmission's speedometer drive gear and converts it to a clean digital pulse signal on the white wire output. The 7/8-18 in. thread matches factory GM/Mopar spec, the 0.104" driver key engages the existing drive gear without modification, and the quick-disconnect harness keeps the install tidy. Operating range of 8–30 VDC and a temperature tolerance down to -40°C means this sender is reliable year-round in any climate. The main installation consideration is confirming that your speedometer head is calibrated for a 16-pulse input — get that wrong and your speed readings will be off by a fixed ratio regardless of how well the sender is installed.

Key Features

16 pulse/ rev output, Hall-Effect

0.104" driver key

Quick disconnect/cable wire harness included

For GM/Mopar transmissions type

Working voltage: 8-30 VDC/ Temperature range: -40C ~ +80C.

Specifications

Type
Hall Effect Speedometer Sender
Output
16 pulses per revolution
Thread
7/8-18 in.
Driver Key
0.104 in.
Wiring
Red (+12V), Black (Ground), White (Signal Output)
Working Voltage
8–30 VDC
Temperature Range
-40°C to +80°C
Application
GM / Mopar transmissions
Harness
Quick-disconnect cable included

Pros & Cons

👍 Pros

  • Direct replacement for mechanical speedometer drive on GM/Mopar transmissions — no adapter or fabrication needed.
  • 16-pulse Hall effect output delivers consistent, accurate electronic signal for compatible gauge heads.
  • Wide operating voltage (8–30 VDC) accommodates both 12V and 24V systems without modification.
  • Quick-disconnect wire harness included — clean install with no loose wire splicing at the transmission.
  • Rated to -40°C, so it handles cold-climate use without false readings or signal dropout.

👎 Cons

  • Pulse output is fixed at 16/rev — if your speedometer head requires a different pulse count, this sender alone won't calibrate correctly.
  • Fitment is GM/Mopar-specific; Ford or import transmission tail housings with different thread or drive configurations are not compatible.
  • No installation instructions reported in the box — experienced builders will be fine, but first-timers may need to research torque specs and connector orientation separately.
  • Thread spec is 7/8-18 in. — confirm your transmission housing matches before installation to avoid cross-threading.

Frequently Asked Questions

It's designed for GM and Mopar transmission tail housings that use a mechanical speedometer drive gear — common in older muscle cars, trucks, and hot rod builds running a TH350, TH400, 700R4, or similar trans.
That's the key dimension that engages the transmission's speedometer drive gear. It needs to match your trans's driven gear slot — verify your transmission's speedo drive spec before ordering to confirm fitment.
The 9220 outputs 16 pulses per revolution. This must match what your electronic speedometer head expects. If your gauge requires a different pulse count (e.g., 8 or 24), you'll need a signal converter or a different sender.
Yes — a quick-disconnect cable wire harness is included. The three wires are Red (+12V supply), Black (ground), and White (signal output). Standard hookup, no splicing required if your gauge uses matching connectors.
8–30 VDC, so it works fine in both 12V and 24V vehicle electrical systems. Temperature range is -40°C to +80°C, which covers everything from a Minnesota winter to an engine bay in summer.

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