The R79
W was first released in 1970 and what was included on the 1970 Chevelle LS-5 & LS-6 package as RPO T-60,and available a side option also under RPO T-60 on the L-34 & L-78 Chevelles.
I think Cumby is too busy..

...so here is my NOS R89
W,which was newly released in 1971,which is nearly indentical in every detail to the R79
W.