The mounts were used on Novas and Camaros. Same parts.
On Novas I have discovered that 113 and 114 were used in 69 up until sometime mid 70 model year.
So I have observed:
Top 3912598 RH & 3912597 LH 67-68 Big Block engine frame mounts. This is physically different than the later years.
Pictured below 3950114 RH and 3050113 LH 69 Nova and Camaro and 70 Nova until mid year. At least November 69.
Middle 3980942 RH & 3980941 LH 69-70 Big Block engine frame mounts. Used on Nova 2nd half of the model year.
Greg