Prestolite Alternator 12V 320A 4890JB

This Prestolite alternator is a new 12V unit rated at 320A, with part number 4890JB. It is listed as an OE product and uses an internal regulator, which is a useful checkpoint when matching the charging system configuration on the vehicle or equipment.

The alternator is configured with a twin leg mount, CW rotation, and an AC (R) terminal self-excitation note. Key mounting dimensions include 101mm inside mounting legs, 215mm mount centre to centre, a 13mm pivot hole diameter, and a 1/2 UNC adjusting hole diameter.

Physical details matter with rotating electrical parts, especially on higher output units like this 320A alternator. The shaft diameter is 22mm, the pulley section is not applicable, and the unit weight is 14.5kg, so it is worth checking both the mounting layout and available space before ordering.

Key Features

• Prestolite OE product
• New alternator
• 12V system
• 320A output
• Internal regulator
• Twin leg mount

Specifications

• Part number: 4890JB
• Brand: Prestolite
• Product type: Alternator
• Voltage: 12V
• Power rating: 320A
• Condition: New
• Warranty: One Year
• Unit of measure: Each

Application and Buying Notes

For fitment, the most important identifiers here are part number 4890JB, Prestolite brand, 12V voltage, and the 320A output rating. If you are replacing an existing unit, compare the mounting style and dimensions carefully: twin leg mount, 101mm inside mounting legs, 215mm mount centre to centre, 13mm pivot hole diameter, and 1/2 UNC adjusting hole diameter.

The regulator type is internal, and the note states AC (R) terminal self-excitation. That means the charging system setup should be checked before purchase, because alternators with different excitation or regulator arrangements are not interchangeable in every application. The rotation is clockwise, so direction also needs to match the original arrangement.

The shaft diameter is 22mm and the unit weighs 14.5kg, which can help when comparing against the removed alternator or checking installation access. The pulley section is listed as not applicable, so do not assume a pulley specification from other parts or similar-looking units.

Because fitment details are not provided in a vehicle list, the safest approach is to verify the existing alternator tag, mounting points, electrical connections, and system type against the 4890JB listing before ordering. If there is any mismatch in voltage, regulator type, rotation, or mount dimensions, the part should be checked again with a parts interpreter.

Before supply, the safest approach is to confirm the original unit details against the listed part number, voltage, output rating, mounting arrangement, and pulley configuration. That checking process is standard practice in the parts trade because visually similar units can still differ in service-critical ways.

For workshop, fleet, and equipment applications, accurate identification of part number 4890JB helps avoid unnecessary freight, additional labour, and vehicle or machine downtime. Where the application is not straightforward, the original unit, OEM reference, or workshop records should be used as the primary confirmation point.

Relevant published details for this unit include Type ALTERNATOR, Unit of Measure EACH, Warranty One Year, Inside Mounting Legs 101mm, Power Rating (Amp) 320, Regulator Type Internal, Shaft Diameter 22mm, Voltage 12, Alternator Mount Twin Leg, New / Reman. New.

Additional published details for cross-checking include Weight 14.5kg, Product Group 1 ROTATING ELECTRICAL, Part No. 4890JB, Brand PRESTOLITE, Description Prestolite Alternator 12V 320A, Adjusting Hole Diameter 1/2 UNC, Pivot Hole Diameter 13, Pulley Section Not Applicable, Rotation CW, Suits Unit Make Prestolite.

Prestolite Alternator 12V 320A. Part number 4890JB should be checked first. Listed voltage is 12. Listed output rating is 320. These details form the core reference points used by parts interpreters when confirming the correct replacement.

Mount style is Twin Leg. Regulator type is Internal. Pulley configuration is Not Applicable. Those physical and electrical details should line up with the original unit before the replacement is approved for fitment.

For part number 4890JB, the normal identification sequence is part number, electrical rating, mounting arrangement, connector or terminal style, and pulley or drive details. Using those checkpoints helps confirm that the listed unit matches the service requirement rather than only looking similar.

For a alternator in workshop, fleet, trade, agricultural, or construction service, the listed voltage 12 and output 320 should be checked carefully. Incorrect selection can affect installation time, return freight, and equipment availability.

Compatibility note: Confirm compatibility using part number 4890JB, Prestolite brand, 12V 320A rating, internal regulator, CW rotation, twin leg mount, and the stated mounting dimensions before purchase.

FAQ

What is the part number for this alternator?

The part number is 4890JB. For this listing, part number 4890JB is the main reference point. Listed voltage is 12. Listed output rating is 320. These details should still be checked against the original unit before ordering.

Is this alternator new or remanufactured?

It is listed as new. For this listing, part number 4890JB is the main reference point. Listed voltage is 12. Listed output rating is 320. These details should still be checked against the original unit before ordering.

What voltage and output does it have?

It is a 12V alternator with a 320A power rating. For this listing, part number 4890JB is the main reference point. Listed voltage is 12. Listed output rating is 320. These details should still be checked against the original unit before ordering.

What type of regulator does it use?

It has an internal regulator. For this listing, part number 4890JB is the main reference point. Listed voltage is 12. Listed output rating is 320. These details should still be checked against the original unit before ordering.

What mounting and size details should be checked?

Check the twin leg mount, 101mm inside mounting legs, 215mm mount centre to centre, 13mm pivot hole diameter, and 1/2 UNC adjusting hole diameter. For this listing, part number 4890JB is the main reference point. Listed voltage is 12. Listed output rating is 320. These details should still be checked against the original unit before ordering.

Does this listing include vehicle-specific fitment?

No vehicle list is provided, so fitment should be confirmed against part number 4890JB, the alternator mounting layout, and the original unit details. For this listing, part number 4890JB is the main reference point. Listed voltage is 12. Listed output rating is 320. These details should still be checked against the original unit before ordering.