Hello argo

Welcome to these forums.

Unfortunately, the industrial engines numbering system has been lost.
Perhaps the 'Y' may have indicated the equipment manufacturer.

However, we should be able to tell you more with some images.
We have some identifier parts lists here:
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=52936

For information on uploading images click HERE.

Hope this helps.
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Jack