Do timing belts need to be replaced on old cars and when should i change mine?

i have 1992 cadillac brougham 5.7 v8 350 and was wondering when should i change the timing belt on it? if the engine was rebuilt or new would they have changed the belt?|||You can look at it and see if it is worn. if it is rubber it will last long, but if it is a chain, than you should change it.|||dont fix thing that are not broken really depends on if its a belt of chain and then if so belt should be change at 100,000 miles and new or rebuilt yes most likely was replace i wouldnt worry about it and really only way is by knowing the miles and if it has been change id be more worried about if it was going to snow next week or not than replacing timing belt if its running leave it a lone