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GM Turbo 400 Stock Capacity Transmission Pan

Part Number 9591

PML TH400 stock tranny pan, as-cast
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PML TH400 stock tranny pan, powder coated
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PML TH400 stock tranny pan, polished
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As-cast finish
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Black powder coating
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Polished finish
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Volume: stock capacity

Dimensions: Click here for dimensions. Although this pan is stock capacity, it is still larger than the stock pan. Always check your vehicle for clearance before ordering. Fin height is about 0.270 inches.

Number of Bolts: 13

The PML GM Turbo 400 stock capacity transmission pan fits many cars and trucks with the GM TH 400 transmission. This transmission is found in GMC and Chevy vehicles such as:

  • 1970-76 models of Corvette, Chevy, Cadillac, Olds, Buick
  • Blazer (2WD and 4WD)
  • K1500, K2500, K3500 (2WD and 4WD)
  • Jaguar
  • Jeep
  • Ferrari

The transmission was first available in 1964.

If your stock pan has a dipstick receiver on the side of the pan, a PML Turbo 400 is not compatible with your vehicle.

PML also offers an extra capacity deep pan for these applications. The deep pan has the same capacity as the stock truck TH 400 transmission pan.

The TH400 transmission is called Super Turbine 400 or Turbo 400 in the racing field and is formally called THM400 for Turbo-Hydra-matic 400. It first appeared in cars in 1964 and continued in production in the 1980s. In 1980s GM changed the name to 3L80.

drain on PML TH400 pan

Drain and Options for Temperature Sensor

The pan has a drain on the right (passenger) side and a boss on the driver (left) side that can be machined for a temperature sensor.

Temperature sensor unit machining is an additional cost. That option can be added in the shopping cart.

Included with PML TH400 pan

Included With Pan

PML includes new mounting bolts, a magnetic drain plug, and washer with each pan.

The drain plug has a copper sealing washer.

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Inside of PML TH400 pan


This PML pan features an open interior to clear the valve body. The hole for the drain is visible at the bottom of the image.

PML Transmission Pan Compared to Stock

PML Transmission Pan Part Number 9591 height compared to stock  PML Transmission Pan Part Numbers 9591, compared to stock
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These images show this PML transmission pan compared to the stock pan.


Dominant Performance Transmissions installed PML's TH400 transmission pan on a 1966 Impala SS Convertible 396 during a transmission upgrade to add strength and cooling.

GM Turbo 400 transmission pan from PML on 1966 Impala  Click on image to view larger.

PML Transmission Pan Features:

  • Sand-cast aluminum with raised fins
  • 3/16-inch thick wall construction to add strength to the transmission case
  • 3/8-inch thick gasket flange will not bend when bolts are tightened
  • Machined gasket surface for a secure seal
  • Boss cast into pan can be machined for a temperature sensor
  • Drain hole and magnetic drain plug for easier, less messy maintenance

All PML transmission pans ship with new mounting bolts and a magnetic drain plug.

If you would like PML to machine your pan for a temperature sending unit, there is an additional charge of $45 .

Find out why you should buy a PML transmission pan.

Learn more about finishes and construction of PML parts.

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