2024 Grand Design Momentum 399TH vs 2025 Grand Design Momentum M-Class 350M

Detailed Comparison

Two noteworthy RVs face off: the 2024 Grand Design Momentum 399TH and the 2025 Grand Design Momentum M-Class 350M. From dimensions to amenities, here's the full breakdown.

Starting with size, the Grand Design Momentum 399TH measures 28.0 ft long and tips the scales at 8,300 lbs dry weight. The Grand Design Momentum M-Class 350M comes in at 42.0 ft with a dry weight of 10,500 lbs. That gives the Grand Design Momentum M-Class 350M roughly 14.0 extra feet of length.

Capacity-wise, expect to sleep 9 in the Grand Design Momentum 399TH versus 9 in the Grand Design Momentum M-Class 350M. With 0 and 3 slide-outs respectively, the parked floor plans differ significantly.

Tank capacities are a key off-grid consideration. The Grand Design Momentum 399TH carries 68 gal of fresh water, 70 gal gray, and 50 gal black. The Grand Design Momentum M-Class 350M offers 78 gal fresh, 70 gal gray, and 38 gal black. The Grand Design Momentum M-Class 350M has the edge for extended dry camping.

Budget-wise, the Grand Design Momentum 399TH is listed at $61,000 compared to $81,000 for the Grand Design Momentum M-Class 350M.

For family camping trips, the larger floor plan and additional berths make a real difference. For boondocking, the model with superior solar and battery setup will keep you comfortable off the grid longer. If you're going full-time, the larger tanks and more robust build quality matter enormously.

The numbers tell one story, but the feel of a floor plan is personal. Schedule a walkthrough before you decide.