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• 2004 MOUNTAIN AIRE 3778

2004 Newmar Mountain Aire 3778 

Extremely well maintained 2004 Newmar Mountain Aire 3778, a luxury Class A gas motorhome that delivers premium features in a reliable package.  This coach offers significant service history with all systems fully functional.  The unit has been actively used through 2025 and is in excellent condition.   

Highlights include:

• Only 78,354 miles!
• Reliable Ford 6.8L V10 gas engine with automatic transmission
• Spacious two-slide floorplan (living/dining & bedroom)
• Full residential kitchen with convection microwave, refrigerator, and cooktop
• Private bedroom suite with queen bed and abundant storage
• Full bathroom with shower, vanity, and porcelain toilet
• Dual ducted A/C units and efficient furnace for year-round comfort
• Onan generator for off-grid capability
• Ample basement storage with side-swing doors

This coach has been extremely well maintained.  There has been significant maintenance and service performed in past 5 years (all records maintained and summary provided below).  It is ready to go now with all systems in working order - ready for new adventures.

Specifications

General

• Year / Make / Model: 2004 Newmar Mountain Aire 3778
• VIN: 5B4MP67GX43378453
• Class: Class A Gas Motorhome
• Chassis: Ford F-53
• Engine: 6.8L Triton V10 (gasoline)
• Transmission: Ford TorqShift Automatic with overdrive
• Mileage: 
• Length: 37 ft 11 in
• GVWR: ~22,000 lbs
• CCC: 2,507 lbs
• Towing Capacity: 5,000 lbs hitch rating

Dimensions

• Overall Height: 12’ 8”
• Interior Height: 82”
• Fuel Tank: 75 gallons (gasoline)
• Fresh Water Capacity: 85 gallons
• Gray Water Capacity: 65 gallons
• Black Water Capacity: 45 gallons
• Propane Tank: 25 gallons

Condition & Notes

• Non-smoking coach, extremely clean interior
• All systems in good working order

Recent Service History Since 2020:

• 07/07/2025 – New Rear Air Conditioner.  $1,500.00
• 1/22/2025 - New O2 Sensors, Catalyst Driver side, exhaust pipe gasket.  $4,460.96
• 11/01/2024 – New House Batteries (two Group 24 Interstate).  $178.70
• 09/30/2024 – Solenoid Valve new.  $378.17
• 01/05/2023 – Replace brake pads (4 pads total) $245.36
• 06/24/2021 – Inspection, Fuel Filter, and dryer filter.  $1,160.40
• 01/08/2021 – Replace both knock sensors, pigtails.  $507.68
• 12/15/2020 – Front AC Recharge, Spark Plugs, Chassis Lube. $1,101.94
• 10/5/2020 – Workhorse Front & Rear Steering Track Bars upgrade, Safe-T-Plus.  $1,669.00