Majestic  models 551 and 651 look quite similar. Both use the same cabinet but that's where the similarities end.  Model 551 incorporates a power transformer and a short-wave band. Model 651 lacks this feature.

Majestic 651 ca: 1937

The tube line-up, model 551; 41, 75, 6A7,6D6 & 80
Model 651; 25L6, 75, 6D6, 6A7, 25Z5 & ballast. #L48B.

Year: 1936 & '37
Cabinet: Bakelite or painted Bakelite
Back: molded Bakelite
Dial: airplane style, back-lit
Tuning type: capacitance, super-het