Besides the higher temperature rating (105 degrees C) and more capacitance, they are extremely small.  Approximate size is 1" to 1 1/8" in diameter by 1 1/8" to 1 1/4" tall, depending on current stock.  Appearance may be different from pictures below.  These have solder pins designed for snap-in placement into a printed circuit board and are not a direct physical replacement for the old Heathkit capacitors which have a different mounting arrangement.  However, these are small enough that they can be mounted in most equipment using a little ingenuity, such as using wire ties.  They may mount directly on some Heathkit PCB's with drilling different holes, such as the PS board in the SB-200 amplifier.  These are small enough to be placed inside and underneath the chassis of the HP-23 series of power supplies.  Other Heathkits, such as the SB-401 transmitter, can use these value capacitors.  It may be possible to modify or craft a new mounting wafer used with some of the old Heathkit capacitors to accept this smaller capacitor.  Whatever mounting arrangement you decide to use, make sure it is safe and secure so that it does not become a hazard.    

Being sold here is the capacitor.  Mounting and wiring is up to you.  

Order Part No.  HV-cap  at any of the following parts pages:

 SB-401 Parts       HP-23 Parts

Click on pictures below for larger views of this mighty little capacitor.