The intake manifold on our beloved GMC has a problem, one that everyone has to be careful of and I feel attend to.  Whether you have this problem now or not, if not you will soon so my suggestion is to attend to it now.  Here is a story of someone who had it happen and took heed of the call.  I appreciate the support Tom D. has given me– I would be happy to help any of you with this and other issues with your coach.  If you want to learn more about this problem, give me a call.  Here’s a letter I got from a customer, see if this might sound like you:

Early January 2011, local mechanic complete tune-up on the GMC 455 new plugs & wires, said he touched carburetor, distributor and all the items to assure improved gas mileage and a trouble free trip.  My son and I departedSpringfield MO @ 8:00AM  Saturday and pointed the nose toward Marco Island FL.  Only 25 miles out of Spfld, and the sputtering, missing and minute backfiring returned.  Being and old aviator “lots of old”, I told son that we had passed the point of return and would charge on to FL.  In spite of cold weather, holes in the hyw in Alabama big enough to bury horses in and an average MPG of 6.6 we made good time.  In Clear water Sunday night and Naples early Monday.  After time in south FL begin a return north and into Orlando to have Jim Bounds take a look at the sick 455.  Not much wrong, cracked plugs, burned wires and a minor problem called a cracked intake manifold.  Guess the local mechanic burned his mouth on his coffee and in the excitement missed those minor things.  What to do?  Decided to drive it back to MO and again try to pass the test for “Shade Tree Mechanic”.  This decision was based on Jim Bounds providing me with required parts and talking me through the necessary steps by phone, 1200 miles away.  Jim had to sell two GMC’s to pay his phone bill.  However, the point of this story is to assure all that it is and will be just as Jim says it will be.  With Jim coaching me by phone I disassembled, placed the Co-op supplied cross over plates replaced “turkey tray” intake manifold gasket with a Co-op supplied fiber gasket and reinstalled the carburetor and distributor which I had removed and shipped to Jim for rebuilding.  I failed the test because I did a 180 on the distributor installation and had to have some help in this area.  Drove 3,013 miles on the trip with an average of 8.2 MPG.  Running very good now and have an outing next week so will find out what MPG will be after all of the above.
Thanks, Jim
Tom D.