I have a collection of RX crystals for Futaba receivers. They have different colored tags on them. Is there a color code that differentiates SC and DC crystals. If not, how can you tell which ones are dual conversion and which are single conversion crystals? Thanks for any input.

The cystals will have numerical codes that tell you what kind they are. The codes are:

72-3 AM TX crystal ground frequency ch.61 thru 90
72-5 AM TX crystal air frequency ch.11 thru 60
72-7 FM TX & SC RX crystals air & ground
72-9 FM TX & SC RX crystal (same as 72 7) (-9 only on ch.11 thru 15)
72-10 FM DC RX crystal air & ground
72-11 AM RX crystal air & ground
72-12 FM RX short crystal

Note: "SC" = Single Conversion, "DC" = Dual Conversion