Trying to figure what year this TO-35 is

[buckeye021]

I have a TO-35 that seems to be comprised of different year tractor parts. The SN on the dash is SDM183xxx (I believe is a diesel number) but I have a gas engine. The casting codes (if I am reading them right) seem to be 1955, but the paint and badging is more like 1958. It is a dual stage clutch and 12 volt system (I know that could have been upgraded at some point). I would like to figure what year the tractor is so that I can be sure I'm ordering the correct parts for it. I attached some casting images, hopefully someone can confirm if I am decoding them correctly.
Thanks

 

[Cougsfan]

Check out this wed site: Ferguson Serial Numbers
The 183 appears to be a 1958 gas special.