Advice please on removing suction filter

[harrysdad]

Hi. I have a 1958 IH B250d which I use on my small piece of ground. I have been working through her systems over last 8/9 years and hydraulic strip down is on the cards, due to loosing all use of the system last week.
Problem one. Can not work out how to remove suction filter from the lift housing. The stub pipe emerging from the casing appears to be a flush fit [with no shoulders] and a new filter appears to have a collar which seals against the casing. So I can't figure how I can install or remove one if it is a larger diameter.
I have a IH service manual but it does not elaborate on how to extract. If anyone could help I can crack on before the weather turns as my ground becomes rather soft later on. Thanks again, harrysdad.