I don't ever personally recall seeing a TU175 but the TU180 seems to be a fairly common model and I know they made a TU170. They produced a long series of TU models that almost jumped in one HP incriments from 14 to 24 . The 4 digit models are the more "conventional" design and the 3 digit models are the Landhope design with the flat, open operator station. I assume the TU175 would be a 17 PTO HP (or maybe 17.5 HP) model. TBN has an Iseki forum and if you use the search function I'm sure you will find a number of threads about TU models. You may want to post this in the Iseki forum and maybe someone can give you more specific info on the 175.