I would like to thank those who gave advise re rattle under my Blazer, it was indeed the catalytic converter breaking up. Have replaced it with a sport cat and have had a stainless steel dual outlet twin tip powerflow exhaust fitted, sounds good.
The battery then died, which has now been replaced, but now I am only getting very hot air out of the HVAC, this is the computer controlled climate control system, can anybody help? please.
Adrian

 

you need help on how to take it out or where it is?