Ferrous Material Types:

N43  20-250 Mhz
N61 1-25 Mhz
N67 1-50 Mhz
N68 1-100 Mhz

Torroid sizes:

"T30-6"
30 refers to 0.30" outer diameter
6 refers to yellow / 3-40mhz

"FT50-43"
50 refers to 0.50" outer diameter
43 refers to 30/400mhz (shiny black)

0 = 50-350 Mhz (tan)
1 = 150 khz - 3 Mhz (blue/clear)
2 = 250 khz - 10 mhz (red/clear)
3 = 20 khz - 1 mhz (gray/clear)
6 = 3 mhz - 40 mhz (yellow/clear)
7 = 1 mzh - 25 mhz (white/clear)
10 = 15-100 Mhz (black/clear)
12 = (yellow/clear)
15 = (white/clear)
17 = 20-200 Mhz (blue/yellow)
31 = 1-30 Mhz power 1-300 Mhz transformer (black)
43 = 1-30mhz power 5-400 transformer (shiny black)
61 = 20-500 Mhz transformer (dull black)
75 = 1-3 Mhz power 1-50 Mhz transformer
77 = up to 100 khz (shiny black)

0, 6, 7, 10, 71, 31, 43, 61, 75 are good for HF

Full reference on toroid sizes, as well as uH calculator here:
http://toroids.info/T50-10.php

more data at http://www.ferroxcube.com/prod/assets/fertor.htm

the big pack I got were 11/16" OD type 43  aka FT68-43