<p>The strong far-infrared (FIR) difluoromethane ¹²CH₂F₂ laser was discovered over 45&#xa0;years ago. This paper focuses on the isotopic carbon-13 difluoromethane (¹³CH₂F₂) molecule, which was identified as having a good overlap with the ¹²CO₂ laser pump bands. Prior research has resulted in the generation of over 100 laser lines, many of which have had their frequencies precisely measured. This paper extends the work previously performed on assigning these laser lines, as well as determining the molecular constants for the <i>v</i> = 1 excited state of the ν₉ and ν₃ vibrational bands. This work, when combined with prior investigations, has enabled the assignment of almost all known ¹³CH₂F₂ FIR laser lines_. This includes tentative assignments for predicted laser lines or for those not having a measured frequency along with new values for the A, B, and C rotational constants and band-center frequencies for the ν₉ and ν₃ modes.</p>