Orry,
The "Narrow Frame" Cub Cadets are the following series: the 70/100, the 1x2/3-71, the 1x4/5-72 and the 1x6/7-73 series. With the 70/100 both are gear drive, the 70 being 7hp and the 100 being 10 hp. The x in the 1x2/3 -71 series could be a 0 (10hp) or a 2 (12hp) for 102, 122, 123 and 71, the 71 was a 7hp. The 102, 122 and 71 were gear drive and the 123 was hydrostatic drive. Then there's the 104, 124, 105, 125 and the 72. The 104, 124 and 72 were gear drive, the 105 and 125 were hydrostatic drive. This series also added front QA or Quick Attach, all the previous series had bolt on or pin on attachments. With the 1x6/7-73 series there's also a 14hp model. 106, 126, 107, 127, 147 and 73. The 106, 126 and 73 were gear drive, the 107, 127 and 147 were hydrostatic drive.
The "Wide Frame" Cub Cadets are the 1x8/9-86 series and the Quiet Line series. The 1x8/9-86 models are the 108, 128, (gear drive) 109, 129, 149, 169 (hydrostatic drive) and the 86 which was an 8hp gear drive. As you have probably guessed the 169 is 16hp. The Quiet Line series were the 800, 1000, 1200 (gear drives), 1250, 1450 and 1650 (hydrostatic drive).