Hey I have a 72 blazer with 4inch susp. and 3 '' body with 38''tires. Its a automatic with 205 transfer case. When I am driving at highway speeds and let off the gas I get this really loud vibration from my t-case or driveline and sometimes when I step on it as well and I dont know what is causing this. The driveline isnt at a steep angle so what could it be.