What year truck are we discussing here? Some older titles used the engine number as a means of identification, so it's possible that's what the ID number on the title refers to. If the engine hasn't been swapped out since the truck was new, try looking on the machined pad near the distributor on a 6-cylinder truck, or on the engine block ahead of the passenger's side cylinder on a V-8. (Chevy truck, I presume?)
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!