Take the distributor cap off and then rock the crankshaft harmonic balancer/pulley assy to and fro. See how much 'lost motion' there is between you moving the crankshaft and the rotor turning. If more than a couple degrees you've got quite a stretched chain. You'll be able to feel the slack in the chain if it's extreme. Replace the timing damper when you're in there as the rubber 'slippers' on the damper will harden with age then break. This will eventually lead to a broken timing chain.
Good News is, a 2.8 with stock cam and rocker arms is not an interference motor. All bets are off, however, if you've changed to a cam with more lift and/or 1.6:1 rocker arms, for increased performance. I don't know anyone who can say for sure whether or not pistons will kiss valves in that case.
The chain broke on my '90 LS (now a 3.4) and before I did the engine swap, the timing set and damper were replaced. No crunched valves or anything.
You can take the timing cover off while in the vehicle, best access is to remove the radiator also. Use the Breaker-Bar-Against-the-Frame-Rail-Then-Bump-the-Starter technique to bust loose the crank nut, then the harmonic balancer is removed with a puller. Do yourself a favor and get a set of Torx bits as you'll need them.
HTH, hopefully with Low Low 120K on the clock she'll be as tight as new......ed
