Could anybody tell me if gearbox parts from the later monoshock dt175  are interchangeable with the 1977 to 1981 175mx models?. Very hard to get gearbox parts here in Ireland or Europe.
Sorry, initally said 1987 to 1981!

Did you mean 1977 to 1981?

MarkT has detailed knowledge and will post a reply later, I'm sure. In the meantime, I wonder if the RT180 parts are interchangeable?

1978 to 1981 USA DT175 and DT125 monoshock trans is the same.  (No 1977 DT175 or DT125 model in USA)

We did not get a DT175 after 1981 so don't know much about models other countries got after 1981.  

What part do you need?
 

Thanks Mark T for your prompt reply. I'm considering a used gear cluster from Germany. 5th and 6th gears are chipped and teeth worn in mine. I would get the appropriate pinions if not too expensive but in Australia and Thialand a version of the dt175 was made up until 2010 or later. I have seen an engine strip on YouTube and the engine and gearbox internals look identical. However they have different part nos. so lm in a quandary 
l have a spare engine but gearbox has similar trouble.
Any table of equivalent oil pumps for the dt175mx l wonder?
 

Here is a gearbox for sale in the UK at a decent price.  

Ebay UK link

Thank you very much Mark!