# Grand Design Solitude 378MBS

> Front bedroom, rear living area, bunk beds, mid bunk

378MBS is a fifth wheel floor plan by Solitude (Grand Design).

## Specs (2025 model year)

| Spec | Value |
| --- | --- |
| Length | 40 ft 2 in |
| Sleeps | 7 |
| Slide-outs | 4 |
| Dry weight | 14,344 lbs |
| GVWR | 18,000 lbs |
| MSRP | $127,405 |

## Model years

2025, 2024, 2023, 2022, 2021. Year-specific specs: `https://rvenvy.com/fifth-wheel-trailers/grand-design/solitude/378mbs?year={year}`

## Overview

What makes the 378MBS interesting is its layout logic: the living room lives in the rear slide, giving it a true room-like feel, while the east/west bed up front stays well away from the noise. The mid-bunk section is legitimately versatile — owners have used it as an office, guest space, or actual bunk room depending on the trip. Grand Design builds the Solitude line with thicker walls and more insulation than most competitors, and the 378MBS adds CRE 3000 suspension and auto-leveling to help manage what is a substantial rig to tow. A kitchen island, desk, fireplace, and washer/dryer prep mean this one is set up for extended stays, not just weekends.

## Floor plan tags

desk, mid bunk, front bedroom, rear living area, mid den

## Inventory

19 units currently for sale priced $39,995 to $102,999: https://rvenvy.com/fifth-wheel-trailers/grand-design/solitude/378mbs/inventory

Floor plan diagram: https://images.rvenvy.com/212187a9e4f54600e98932c4c3e3237616f912983d42d5f8aa82b2d9b84b3918/1024.webp

Canonical page: https://rvenvy.com/fifth-wheel-trailers/grand-design/solitude/378mbs