The spec shows it to be a 'first series' 1850, (that's what the 185 means. There were 285, 385, and 485 series. The 1855 had 585 and 685). The rest shows that it was a wide front with a gas engine. Obviously, your 1850 has gone through some changes over the years.

If you don't mind, could you please list all of the build codes for your tractor, it will help me with my research.