i have a 1989 gmc r3500 with 454 with almost 300000 miles on it and there is a noise coming from the timing chain cover so i think its going bad.i was wondering should i replace it with a standard chain set or a double roller set?also what chain set makers should i look at and witch should i stay away from?Tia.

also forgot to ask its best to replace the sprockets to aint it and not just chain while its apart?

At 300,000 miles, replace it with new of what it had already. It will be fine.

its the stock chain.any idea who makes the stock chains on gms?

Rock Auto has lots of these for your truck. It looks like they sell individual parts from ACDelco and others, and kits. If it'* not ACDelco then I'd go with Melling.