Thanks for all the reply's. This is what I was hoping for, so I get get a little better information. The truck has 1800 miles on it. It has been garaged more than driven. I know that doesn't mean alot, I see new motors going into new vehicles all the time. The motor has 2 bolts going through the top of it. the side cover is not full height. I can post pics later this evening when I get home. As far as me saying " I wonder how many engines have been changed do to lack of research" means just that. I have read alot of people saying they are or have changed there engine because of the casting number 3837004, and I'm just wondering if they really needed too. I probably should have worded my initial post a little different, now that I read it myself it sounds like I have a stack of documents in front of me and I know everything. Wich believe me isn't the case. I am simply looking for other opinions on this topic. It made no since to me that my motor has all the characteristics of a 216 but has a 235 casting number. I have been researching and asking questions for the last 8 months and everything I find seems to be condradicted by another website or document. Our GM rep will be in again this month and I will see about getting some kind of documentation from him to back up his statement of the casting number being used more than once. The T56X engine according to him started production in late 1955 to be put into the new 56 trucks, at the end of the 56 production schedule the "left over" motors GM had wer also put into some 57's until the "overstock" was used. I understand that the Serial number could have been restamped on the engine behind the distributer, but that doesn't explain the build code J108 (Oct,10 of 48) is what I'm assuming this would mean. Either way with this casting date the block would have had to have been built in 48 or 58, and I find no record of the 3837004 casting being used in 58 (or 59). This where I'm stumped. I don't understand the configuration of numbers and so far the closest I've come of making sense of it is to believe what the GM rep told me.
