PAI FGG-0500 Dual Air Pressure Gauge – Mack R Model 7MT320RP2

The PAI FGG-0500 is a premium aftermarket dual air pressure gauge designed for classic Mack R Model trucks. This mechanical gauge features two independent needles to simultaneously monitor primary and secondary air brake system pressures from 0-150 PSI. Built to meet OEM specifications, it's a direct replacement for Mack part number 7MT320RP2 and fits the standard 2-1/8" dashboard cutout found in Mack R series instrument panels. Includes mounting hardware for complete installation.

Signs You Need a New Air Pressure Gauge

• Gauge needle stuck or not moving when air system pressurizes
• Inaccurate pressure readings compared to known-good gauge
• Erratic needle movement or bouncing
• Cracked or fogged gauge lens obscuring visibility
• Gauge face faded or difficult to read
• Air leak at gauge connection or fitting
• One or both needles broken or missing

Specifications

Cross References

This gauge replaces or is equivalent to the following part numbers:

• Mack: 7MT320RP2, 7MT320P2, 25166143

Vehicle Applications

This dual air pressure gauge fits the following Mack truck models:

• Mack R Series (R600, R688, R690, etc.) (1967-1998)
• Mack RD Series (RD600, RD688, RD690, etc.)
• Mack RM Series
• Mack RW Superliner
• Mack DM Series
• Mack U Series

Understanding the Dual Air Pressure Gauge

Heavy-duty trucks use a dual-circuit air brake system for safety redundancy. The primary circuit (typically rear brakes) and secondary circuit (typically front brakes) each have their own air tanks and pressure readings. This dual-needle gauge allows the driver to monitor both circuits simultaneously on a single instrument. Under normal operation, both needles should read approximately the same pressure (typically 110-130 PSI when fully charged). If one needle drops significantly lower than the other, it indicates a leak or failure in that specific circuit, alerting the driver to a potential brake system problem before complete failure occurs.

Installation Notes

This is a mechanical gauge that connects directly to the air system via tubing or fittings. Ensure all air line connections are properly sealed to prevent leaks. The gauge mounts in a standard 2-1/8" round dashboard opening. When replacing the gauge, inspect the air lines and fittings for damage or deterioration. After installation, verify both needles track correctly as the air system builds pressure and that readings match expected values (typically 120-150 PSI when fully charged, with cut-out around 125 PSI and cut-in around 100 PSI depending on governor settings).

Verify your dashboard cutout size and OEM part number before ordering to confirm fitment. This gauge is designed for classic Mack R Model trucks with mechanical gauge clusters.

Handling Time
At All Pro Truck Parts we do our best to ship all orders same day for orders placed before 12:00pm Central Standard Time. Same day shipment is never guaranteed. For standard UPS or USPS shipping, you will typically receive your package in 1 - 5 business days. Shipping times are never guaranteed and All Pro Truck Parts is not responsible for lost or delayed shipments by the carrier. Carrier times vary by distance from shipment origin and may change without prior notice. Shipping price is calculated from package dimensions and weight. Calculated rates for orders will be available at checkout. Orders placed after 12:00pm CST on Fridays will not be fulfilled until the following business day, Monday morning barring a holiday.

Next Day Air Shipments
The cutoff time for UPS Next Day Air is 12:00PM. If you have missed the cutoff time but would still like to place an order for Next Day delivery, please send us a text message or email. We can try to accommodate and ship your order from another warehouse.

Incorrect Shipping prices
All Pro Truck Parts reserve the right to cancel any order, in the event shipping rates are calculated incorrectly at checkout. We will notify you at your provided contact information to give you the option to pay the correct amount, or allow you to cancel the order for a full refund. 

Free Shipping
Select products qualify for free shipping. Qualifying product groups can change without notice. Free shipping will be shipped via UPS Ground, USPS First Class or USPS Priority Mail.  

Domestic Shipping Services

• USPS Domestic Shipping Services
• USPS Priority Mail
• USPS First Class Package
• USPS Ground Advantage
• USPS Priority Mail Express
• UPS Shipping Services
• UPS Ground
• UPS 2nd Day Air A.M. (commercial addresses only)
• UPS 2nd Day Air
• UPS 3 Day Select
• UPS Next Day Air Saver
• UPS Next Day Air
• UPS Next Day Air Early
• UPS Standard

International Shipping Services

• USPS International Shipping
• USPS First Class Package International
• USPS Priority Mail Express International
• USPS Priority Mail International
• UPS International Shipping
• UPS Worldwide Expedited
• UPS Worldwide Express Plus
• UPS Worldwide Express
• UPS Worldwide Saver

Returns
All Pro Truck Parts offers lifetime returns for any reason on NEW, UNOPENED items in the original packaging with exceptions. (See sale items and special order items).
To be eligible for a return, your item must be unused and in the same condition that you received it. It must also be in the original packaging.

Used items (if applicable)
Items marked as USED at the time of sale will be accepted for return up to 30 days from the date of sale. 

Defective items (if applicable)
Defective items under manufacturer warranty will be eligible for return, as well as a full refund for the total amount paid by the customer. The following criteria must be met to be eligible. (a). The part is under manufacturer warranty (b). the manufacturer has determined the part defective for the purchased application. 

Refunds (if applicable)
Once your item is returned and received and inspected, we will send you an email to notify you that we have received your returned item. We will also notify you of the approval or rejection of your refund.
If approved, then your refund will be processed, and a credit will automatically be applied to your credit card or original method of payment, within 7 business days. For order placed by phone through a card terminal, you must call in to initiate the refund. 

Late or missing refunds (if applicable)
If you haven’t received a refund yet, first check your bank account again.
Then contact your credit card company, it may take some time before your refund is officially posted.
Next contact your bank. There is often some processing time before a refund is posted.
If you’ve done all of this and you still have not received your refund yet, please contact us at sales@allprotruckparts.com.

Sale items (if applicable)
Only regular priced items may be refunded, unfortunately sale items cannot be refunded. 

Special Order Items (if applicable)
Special order items may be eligible for a refund. The decision to accept a special order item for refund is left solely to the All Pro Truck Parts management team. 

Exchanges (if applicable)
We only replace items if they are defective or damaged. If you need to exchange it for the same item, send us an email at sales@allprotruckparts.com and send your item to: All Pro Truck Parts, 3948 Interstate 30 W, Caddo Mills TX 75135, United States.

Shipping
To return your product, you should mail your product to: All Pro Truck Parts, 3948 Interstate 30 W, Caddo Mills TX 75135, United States

You will be responsible for paying for your own shipping costs for returning your item. Shipping costs are non-refundable.

Depending on where you live, the time it may take for your exchanged product to reach you, may vary.

If you are shipping an item over $75, it is advised that you use a trackable shipping service or purchasing shipping insurance. We don’t guarantee that we will receive your returned item.
For returned items designated as "Free Shipping", any items shipped to the customer in which the customer did not pay shipping. All Pro Truck Parts will recover the cost of shipping to the customer's address from the refundable amount owed to the customer on the return and inspection of the item.