i do technology at school and my teacher mentioned blender and i saw people making mugs on blender but i just don't think i have the attention span or time to do 3d modaling...
You don't need a long attention span to learn 3D modelling. You can learn it in small blocks and over a period of time. When I decided to learn 3D modelling, I chose a locomotive that I wanted to see in the game. So when I came back to the project after a break, I just carried on from where I left off. Instead of coming home from work each day and spending several hours playing games or watching TV, I spent some of that free time learning 3D modelling.
Building a 3D model takes time. The more detailed the model, the more time it takes. This is why it is unlikely any of the current MSTS/OR modellers that read your post are going to drop what they are currently working on just in order to build a model you want unless they also want it themselves.
If you do decide to go 3D modelling I would suggest Blender over the other modelling programs. The primary advantage is the large number of tutorials on youtube that are aimed at beginners. When I transitioned from gmax to Blender I spent many hours watching the beginner tutorials then going into Blender and trying what I learned. It takes time. It will feel awkward. There will be frustration. But after a while it will become second nature and you will learn the skills and which tools you require to make what ever you want.
After watching the beginner tutorials on how to use the interface and make basic objects, watch some speed builds. Watch the ones where the modeller is making models of cars, planes, guns etc. The tools you use to make these types of 'hard body' objects often differ from the tools used to make characters or organic objects (unless of course you find that is more appealing to you).
In addition to the abundance of help and tutorials, Blender is free, open source and multi platform. It is continuously being updated and improved. It can render photo-realistic images that can help you later in creating textures for models or personalised wallpapers/screen saver images for your computer.
The Z-11 locomotive you want is a good choice for a 3D model. No complex outside valve gear and the boiler and tank are comprised of basic cylinders and boxes. Once you have made those then you will be better placed to tackle the spoked wheels will be interesting to build.
Have a go at building the model yourself. You may find that building a model you want gives more personal satisfaction and long term fulfilment than the short term gratification of downloading a someone else's model.
If you have any questions then just post here. There is sure to be someone that can help.