38RE: a 137-gallon gray tank and a TV-lift rear wall
The figure that sets the 38RE apart is its gray tank. At 137 gal it is 50 gal larger than the 87 gal carried by the 31RL, 37MD, and 39RK, and 62 gal larger than its own 75 gal fresh tank. Combined, its tanks reach 262 gal, the most in the family. A buyer who finds the gray tank full before the fresh tank is empty has the plainest numerical reason in the lineup to look here.
Elsewhere it sits mid-table: 3 of 7 by length at 42 ft 6 in, 4 of 7 by unloaded weight at 15,275 lb, and 4 of 7 by GVWR at 17,995 lb. The hitch is where it costs. Its 2,970 lb pin is 6 of 7, second heaviest after the 39FL, and 19.4% of unloaded weight. GVWR minus unloaded weight leaves 2,720 lb, 5 of 7.
Heartland's current drawing labels the rear wall "TV w/ lift, fireplace". Ahead of it, an L-shaped lounge fills the road-side rear slide, and the door-side slide carries a theater seat, a desk and coffee bar, and a roll-out table. The kitchen sits forward of the living room: an island with a pull-out cutting board, and a road-side slide with overhead cabinets, microwave, and residential fridge. A pantry, entry wardrobe, and linen cabinet lead to a bath with a 36 by 48 inch shower, and the 72 by 80 inch king bed sits up front in its own slide. The tradeoff is traffic: with the kitchen between the living room and the bedroom, every trip from the lounge to the bath passes the island.
Fresh water is 75 gal on every Bighorn, so the 38RE's lead is entirely on the waste side: 187 gal of gray and black combined. It is rated for up to 4, like the 31RL, 39FL, and 39RK, so the larger tank does not come with more beds.
Heartland's current Bighorn 38RE floor plan →Heartland's published 38RE specifications
If the 38RE's gray tank is not the deciding figure
Three alternatives within 1 ft 4 in of its length, each built around a different room. Differences come from the spec table.
9 in longer yet 75 lb lighter, 10 lb lighter on the hitch, and GVWR 205 lb higher, which gives the family's largest margin, 3,000 lb, 280 lb more than the 38RE. It drops a slide and the gray tank drops to 87 gal.
Open record →The five-slide alternativeBighorn 39FL1 ft 4 in longer and 370 lb heavier on the same 17,995 lb GVWR, with 120 lb more on the hitch and one more slide. Its tanks are 74 gal gray and 74 gal black.
Open record →If you need room for 8Bighorn 37MD4 in longer and 375 lb heavier, GVWR 105 lb higher, yet 265 lb lighter on the hitch. It sleeps 8, 4 more, with a Murphy-bed room mid-coach, but carries 87 gal of gray.
Open record →Three questions about the 38RE's rear living room
- Raise the TV on its lift and sit in both the L-shaped lounge and the theater seat. The two sit in opposite slides, so check the view of the rear wall from each.
- Close both rear slides and see whether an aisle to the rear wall is left between the lounge and the theater seat and table.
- Ask how the 137 gal of gray capacity is divided and where the dump valves sit, since that capacity is the figure that sets this plan apart.
How the 38RE's numbers and room labels were read
Weights, dimensions, tanks, and sleeping capacity are from the spec table in Heartland's 2026 Bighorn brochure (Rev. 2/26), last checked here on 2026-08-15. The room labels come from Heartland's current 2027 Bighorn 38RE drawing, read on 2026-09-26, because the brochure prints its 2026 drawing too small to read. The two model years may differ, so check the exact 2026 unit against the 2027 drawing. The slide count is from RVUSA's 2026 spec guide and matches the four slide boxes on the 2027 drawing. Heartland footnotes that some specs at the time of print may include estimates.