Wow, nice dad you got there.
Heres what I suggest before doing any mods...to prolong its life
At 100k, you might want to bring it up to snuff maintenance wise before even thinking about a lift kit/oversize tires, etc.
Flush transmission & replace filter.
Change fluid in both differentials and replace with a high quality synthetic gear lube (amsoil severe gear) *just a recommendation*
Give it some mobil 1 oil and a pure one filter
Replace plugs, wires, fuel filter, PCV valve, air filter (or intake)
Check your oil lines (theres a good chance they're leaking, replace if so)
Do a chassis lube
after all that is done...then sure, lift kit.