Charlie - don't think I ever saw Jonathan's site/link. Can I just copy the chart into a post?
This list isn't gospel but is accurate as far as I know for IH Cub Cadets having a U in the serial number tag. For those of you that haven't seen this list you probably should copy it really quick since it has some off topic info and might get poofed.
International Harvester Cub Cadet and Cadet Product Codes / Model Designations
Following are IH Codes for Tractors/Riders with Serial Number Tags having a letter "U", with
seven digits to the left of the U, and six digits to the right of the U.
First three digits (to the left of the U) identify Product Code. Next four digits identify the Model Designation
Six digits (following the U) identify consecutive unit build number
i.e. 2050042U123456 = The first three digits 205 identify this tractor as a Cub Cadet Garden Tractor, and
the next four digits identify it as a Model 86. The six digits after the U identify it as the 123,456 tractor built
Product Codes (first three digits)
034 Cadet Rear Engine Rider
035 Cadet Lawn Tractor
205 Cub Cadet Garden Tractor
Model Designations (four digits left of letter "U")
205 Cub Cadet Garden Tractors
0036 Model 73
0037 Model 106
0038 Model 107
0039 Model 126
0030 Model 127
0041 Model 147
0042, 0207, 0208 Model 86
0043, 0209, 0210 Model 108
0044, 0211, 0213 Model 109
0045, 0217, 0218 Model 128
0046, 0220, 0221, 0223 Model 129
0047, 0224 Model 149
0048 Model 169
0050, 0510, 0520 Model 800
0053, 0540, 0550 Model 1000
0056, 0570, 0580 Model 1200
0059, 0610, 0630 Model 1250
0065, 0066, 0660 Model 1450
0067, 0070, 0670 Model 1650
0581, 0591, 0597 Model 482
0582, 0592, 0598 Model 582
0583, 0596, 0599 Model 582 S
0584, 0593, 0600 Model 682
0585, 0594, 0601 Model 782
0586, 0588, 0589, 0595, 0602, 0604, 0605 Model 982
0581, 0603 Model 1282
0606 Model 782 D
034 Cadet Rear Engine Rider
0002 Model 60
0006 Model 55
0007, 0008, 0011, 0012 Model 75
0020 Model 95
035 Cadet Lawn Tractor
0001, 0009, 0010 Model 76
0002, 0021 Model 80
0003 Model 81
0027, 0030, 0034 Model 182
0026, 0031, 0035 Model 282
0028, 0029, 0032 Model 382