1969 was the year that Case introduce the new 200 and 400 Series tractors to replace the earlier 100 Series. In hindsight, I'd have to say that they did not have their act together because in 1971 Case introduced the Snap Fast system of connecting attachments to the tractor such as mower decks, utility plow blades for snow/dirt as well as snow blowers. So....... for two years, Case used the same attachment system as they did on the earlier 155/195 models. What does this mean to you?
Well, it means that your tractor cannot make use of the huge pool of Snap Fast decks, blades and snowcasters that are out there unless you can find the adapter kit that would convert your tractor's frame to accept the Snap Fast models. All of those attachments start with the letter H in their model number and progress to J, K, L, M, N, P, R and S. The attachments that will work with your tractor are the F and G Series and they are a bit more involved to mount and dismount compared to the Snap Fast models.
You tractor will accept a three point hitch or a sleeve hitch for rear-mounted attachments and a hydraulic PTO can be mounted back there to power attachments that need hydraulic power.
If you go to the Tech Library/Parts Manuals, you will find manuals for G and H Series tillers, decks, snow blowers and blades and that will help you understand what those look like.
If you go into the FAQ's section, you will find documents that deal with changing out the hydraulic oil, trans-axle oil and what oils you should select. You may find several documents of interest in the FAQ's that will educate you further about your tractor.
As for parts interchangeability, that is determined this way.
You examine the Parts Manual for your tractor and locate the part number of the item you seek. You can then move to the next manual and the next manual to see if the part numbers match. There is no such thing as a cross-reference index. Case changed the way they built these tractors over the years and that's why there are so many manuals for each model. Those manuals express the various changes made. However, you should also be aware that Case often changed the part number whenever they sourced essentially the same part from a new supplier and that adds confusion to the mix.
If you are confused about something, then that's what the forum is for. ASK.