Specs for the EH101 and the CH149 are identical (at least to me)

Specifications (Merlin HM1)

Crew: 4

Capacity:

24 seated troops or

45 standing troops or

16 stretchers with medics

Length: 22.81 m (74 ft 10 in)

Rotor diameter: 18.59 m (61 ft 0 in)

Height: 6.65 m (21 ft 10 in)

Disc area: 271 m² (2,992 ft²)

Empty weight: 10,500 kg (23,150 lb)

Useful load: 5,443 kg (12,000 lb)

Max takeoff weight: 15,600 kg (32,188 lb)

Powerplant: 3× Rolls-Royce/Turbomeca RTM322-01 turboshafts, 1,725 kW (2,312 shp) each

Performance

Never exceed speed: 309 km/h (167 knots, 192 mph)

Range: 1,389 km (750 nm, 863 mi)

Service ceiling 4,575 m (15,000ft)

Rate of climb: 10.2 m/s (2,000 ft/min)

Disc loading: 53.8 kg/m² (11.01 lb/ft²)

Power/mass: 284.9 W/kg (0.174 shp/lb)

General characteristics

Crew: 5

1-Aircraft Commander, 1-First Officer, 1-Flight Engineer, 2-SAR Techs

Capacity:

30 seated troops or

45 standing troops or

16 stretchers with medics

Length: 74 ft 10 in (22.81 m)

Rotor diameter: 61 ft 0 in (18.59 m)

Height: 21 ft 10 in (6.65 m)

Disc area: 2992 ft² (271 m²)

Empty weight: 23,150 lb (10,500 kg)

Useful load: 5,443 kg (12,000 lb)

Max takeoff weight: 32,188 lb (14,600 kg)

Powerplant: 3× General Electric T700-T6A1 turboshafts, 1,723 shp (1286 kW) each

Performance

Never exceed speed: 167 knots (192 mph, 309 km/h)

Range: 750 nm (863 mi, 1389 km)

Service ceiling 15,000ft (4575 m)

Rate of climb: 2000 ft/min (10.2 m/s)

Disc loading: 53.8 kg/m² (11.01 lb/ft²)

Power/mass: 0.174 shp/lb (284.9 W/kg)

So shouldn't the parts be interchangable?