The resulting value of NewFieldValue is "999-99-99" which sort of makes sense in that it is nine characters, but why did it not strip out the "-" in the original value? This works if I just substitute "-" for the AlphaToStrip in the TRANSFORM.

FieldValue = "999-99-9999"
AlphaToStrip = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ`!@#$%*()-_=+[{]}\;:,<.>/?"'
NewFieldValue = EVALUATE("ALLTRIM(TRANSFORM(STRTRAN(FieldValue,AlphaToStrip,''), '@R " + REPLICATE('9',FieldLength) + "'))")