The last I checked, both OKC and WTC1 were not suicide truck bombings. Both trucks were on timers, with the guy who drove the truck up getting into a getaway car after setting the timer.
Whether there was a "suicide" involved for most people is a distinction without a difference. However, the tactic of vehicular bombings utilizing trucks is not new and has proven to result in massive causalities whether a terrorist was included in the body count or not.