Own the series but cannot find out how old Jax was when his dad died

He was born in 1940 and died in 1993, so he would have been 52 or 53, depending on what month he died. Also, my dad was also born in 1940 and died in 1993.

JT died in 1993, and Jax was born in 1978, so
1993-1978= Jax was 15.