The trouble with using statistical analysis on something like this is that, to your buyer, the only data point that matters is the truck you’re trying to sell him. If the average truck can make it to 110k miles on the original timing belt, that’s really neat, but doesn’t help me much if mine is a statistical outlier and breaks at 94k. So putting myself in the position of a potential buyer of your truck, I don’t care about your statistics. I care about whether you followed the scheduled maintenance.
Most people who know enough to ask about timing belts know that the 90k (or whatever) mileage recommendation is one with a safety margin built in. That’s as it should be. Note that it’s called a safety margin, not a cheapskate margin; you change it as scheduled so that you don’t go in to that safety margin.
Having just come off of a T-belt job for someone else who had gone slightly into the “safety margin” and having seen the condition of the belt, I’m still an advocate for not getting into the safety margin.
Also as a potential buyer, I’m going to see that you decided to comfort yourself with statistics as an excuse for not changing the belt on time, and I’m going to assume that you did the same thing with all the other things you’re supposed to do with the car. So now I’m assuming that you failed to break the engine in properly, and you didn’t get the oil changed when you should, and you didn’t change the transmission fluid when you should, etc etc. I’m going to assume that you’re trying to sell me a ticking time bomb, and I’m going to go give my money to someone who did what the manual said they were supposed to do.
Because statistically, a poorly-maintained vehicle will have more problems than one that was properly cared for.