Gst sale of capital goods on which itc is availed

It shall computed as per Rule 44 (6) & sub rule 1(b)
Rule 40 Covers the provision of Sub section of 18 (1)(c),(d) of section 18 , yes Rule 40 (2) says about sub section (6) of 18 but In Rule 44 (6) & Rule 44(1)(b) specifically with illustration lays out the rule for same.

Hence follow Rule 44(6) CGST Act