This is a summary for (hopefully) all ordering part numbers for the AMD-K6®-Processors

AMD-K6   /300    A  F  R
  |        |     |  |  |
  |        |     |  |   ------ Case Temperature
  |        |     |  |          K = 0°C - 80°C     (mobile K6-2)
  |        |     |  |          Q = 0°C - 60°C     (K6-2)
  |        |     |  |          R = 0°C - 70°C     (K6, K6-2, K6-2E, K6-III)
  |        |     |  |          X = 0°C - 65°C     (K6-III)
  |        |     |  |          Z = 0°C - 85°C     (mobile K6-2, K6-2E)
  |        |     |  |
  |        |     |   --------- Operating Voltage
  |        |     |             C = 1.9 V - 2.1 V (Core) / 3.135 V - 3.6 V (I/O)     (mobile K6-2)
  |        |     |             D = 2.0 V - 2.2 V (Core) / 3.135 V - 3.6 V (I/O)     (mobile K6-2)
  |        |     |             F = 2.1 V - 2.3 V (Core) / 3.135 V - 3.6 V (I/O)     (K6, K6-2, K6-2E, K6-III, mobile K6-2)
  |        |     |             G = 2.2 V - 2.4 V (Core) / 3.135 V - 3.6 V (I/O)     (K6-2)
  |        |     |             H = 2.3 V - 2.5 V (Core) / 3.135 V - 3.6 V (I/O)     (K6-2, K6-III)
  |        |     |             M = 1.8 V - 2.0 V (Core) / 3.135 V - 3.6 V (I/O)     (K6-2E, )
  |        |     |             N = 1.7 V - 1.9 V (Core) / 3.135 V - 3.6 V (I/O)     (mobile K6-2)
  |        |     |
  |        |      ------------ Package Type
  |        |                   A = 321-pin Ceramic Pin Grid Array (CPGA)     (mobile K6-2, K6, K6-2, K6-2E, K6-III)
  |        |                   B = 360-pin Ceramic Ball Grid Array (CBGA)    (mobile K6-2)
  |        |
  |         ------------------ Performance Rating
  |                            /500     /550
  |                            /475     /450
  |                            /433     /400
  |                            /380     /366
  |                            /333     /300
  |                            /266     /233
  |
   --------------------------- Family/Core
                               AMD-K6
                               AMD-K6-2
                               AMD-K6-2E Embedded Processor
                               AMD-K6-III