17R had a D333 engine up to SN 00464, after that a 3306. These would be 72 models. I don't have good knowledge of these tractors, but all I know is from looking to purchase one of these models almost 30 years ago. I remember the 74 and 76A's having a turbocharged engine and the early 10K series not having a turbo. The 10K was a pwer shift tractor sold in the same basic time frame as a 17R. I am using a book called Toolquip which could be wrong. They have in my use to be spot on with the SN info. I hope this helps some, I am by no means an expert on these. At the time I was looking at these I ended up with a TD-15C IH. I had it for 15 years with pretty goo luck, it was a power shift.
FWD