Hi, I have a couple pretty easy questions on the 1990 2500V 6.2 diesel GMC suburban I just got. How much coolant does it take? What would be some key places to inspect for damage or common parts to replace? (It has just over 200,000 showing on the odometer but the previous owner said it has a newer rebuilt engine in it, but not sire exactly how old or how many miles). Right now the heater wont turn on and I am not sure exactly what the problem could be. The radio isn't working (already replaced the fuse and had no luck with just a simple repair, same with the heater) Any ideas on where to start on troubleshooting?