Hello,
do you know JBL LE8T and NFX design are compatible?
Here some specifications:

Nominal Diameter:200 mm (8 in)
Rated Impedance:8 ohms
Sensitivity: 89 dB SPL 1 W. 1 m
Frequency Range: 35 Hz 15 kHz
Recommended Enclosure Volume:20-115 L (3/4 4 ft3)
Effective Piston Diameter:152 mm (6 in)
Maximum Excursion Before Damage:13 mm (1/2in peak to peak)
Minimum Impedance:6.2 ohms ( ± 10% @ 25ºC)
Voice Coil Diameter:50 mm (2 in)
Voice Coil Winding Depth:3.7 mm (0.145 in)
Magnetic Gap Depth:11.9 mm (0.470 in)
Magnetic Assembly Weight:2.8 kg (6 lb.)
Flux Density:0.85 T (8,500 gauss)
Bl Factor: 6.2 N/A
Effective Moving Mass:0.016 kg

fs:45 Hz
Re: 5.5 ohms
Qts:0.49
Qms: 4.0
Qes:0.65
Vas:35 L (1.2ft3)
Sd:0.018 m2 (28 in2)
Xmax:4,6 mm (0.18 in)
Vd:99 cm3 (6 in3)
Le:0.3mH
no (Half space):0.5%
Pe (Max):25 W continuous sine wave

Thanks
Guglielmo