[Amps] Maxwell oil filled capacitors?

[A.J Moss]

Hi group,

     Does anyone have any info on these units, or rather any preference as to which would be best used in an amp HV supply...

Maxwell Cat# 30580 54uF 4.2Kv

Maxwell Cat#38697 35uF 5.1Kv

These I just could not resist at a local electronics 'junque' shop. One (30580) is labelled as being the NOS spare for a defibrilator, and is slightly smaller than it's lower capacitance sibling. Now I don't fancy making an Amateur Defibrilator, but it saves space on electrolytic strings in the PS case.
 
Is it advanced technology (castor oil in the 54uf one, unspecified but non-pcb containing in the other) that makes the size difference, or is there some other issue?

73

Adam