1969 Broadcast Sheet Axle Codes 566 and 568

Have 2 1969 Broadcast Sheets for 1969 Dart and 1969 Barracuda. The axle codes are 566 and 568 respectively. Trying to determine what the proper 3rd member Hsg should be, 741, 489 ?
Any help or links?

Thanks to All!

per GG's "white book":

566 - 3.23:1 with S/G & 1-3/8" pinion 741
568 - 3.91:1 with S/G & 1-7/8" pinion 489

on-line - moparfins.com