Correct; XJJ1 is the "quick spec" RPO for the charcoal vinyl seat in a Silverado.
https://www.gmheritagecenter.com/gm-...tion-kits.html
I can't comment on if the pattern is correct since 99% of all Silverados got the cloth/"velour" seat.
Code 70 is Carmine Red, which looks like your exterior color per the SPID.
K