The 100K mile replacement recommendation is for the M116 and M117 V8s, and I've heard it to be 100-150K miles. V8 timing chains have severe inflections/direction changes that cause more wear on the chains.

I don't know what the word is on the M112 and M113. If you can project evolution, the M119 chain recommendation is something like 150-200K miles. I expect the newer V engines have chains that last even longer.

Sixto
95 S420
87 300SDL