Might buy a 2000 chevy-astro-cargo-van. Should I replace timing chain/belt?

you'll get some others to chime in on this most likely.from what i have seen,read,there is no required maintenance on the chain.people have sent them to the grave yard with several hundred thousand miles and chain still going.just my 1 cent.

If the chain were to break, you may do some serious damage to the engine. With the high of mileage, it's good insurance. I've attached the estimated labor times for the timing chain replacement. Labor Times Comments Factory Regular Severe 3.7 5.6 6.2 Addons Comments Factory Regular Severe w/AC add 0.0 0.3 0.3

Agree with # 2.... The 4.3L has all steel timing componets... They'll wear out the rest of the engine without replacement! Timing chain replacement is a thing of the past on a pushrod engine!.. They finally figured it out after approx 30 years of using fiber coated cam gears!.. Oh,..you may not recall those...... I do!