100,000 miles is nothing for those trucks. They go 400,000 + with regular preventative maintenance.
I only put about 10k on my truck a year. I bought it in 2013 with 95,000 and 8 years later I'm at 175,000. It's gasoline and the only major thing I've done is a timing belt (Toyota 4.7). It still runs like a new one.
