Is this an H3?

Hi I have this attachment and after more info on it is it an H3 it looks like ones I have seen but not sure exactly and have no other idea of where to find out mor einfo, I have googled and googled, but without correct terms I just find the same things  

It looks smaller than a H3, but photos can be deceiving, what diameter is the ram you could then compare it to the size of the H3 I am currently refurbishing, 50mm ram is standard for the H3,( I think)

Chris

I'd agree, from what I know the H3 has the hex caps whereas the H2 has square sockets

Cool thanks peeps I will measure the ram when I am next at the garage

Looks same as my H3 with the big hex caps except for the big red disc on front.
Have you had disc off? mine is just another brass cap as on the top. Maybe yours has been lost or thread stripped out and red disc is to blank hole off so it will still pump.
My brothers H3 has slightly slimmer castings and has the square stamped in caps and a few other minor bits "shaved" lighter/smaller.
we were thinking his is WW2 onwards where they were trying to save materials for war machine production.