Dave, I am in UK and own a MK1 65 with A4-192 engine. I have been chatting with a guy in France with a problem which you might be able to shed some light on.
Is your tractor a US Detroit build or a UK Coventry build??, the reason for asking is Bert in France has what he thought was an A4-192 engine because it has a two piece sump, with the wedge at the back, but it turns out to be an A4-203.
We were not aware the 65 came with the A4-203 in Europe, I thought this was a US only build as the only mention I have seen of such is in my I & T Shop Service Manual which is a US publication.
Hope you, or anyone else, can help,