What model 1800 is your parts tractor? I have the 1800 series B. I think the valve I need is only unique to the series A and B models. The C has a different rock shaft housing and I'm not sure it uses it.

If you have an I/T shop manual or the Oliver service manual for the 1800 I might be able to give you a page number and picture of what I'm looking for. 

Maybe I should make a road trip and come see what you have. You might have something better that I could use on mine.

Thanks again.