I ran across this on ebay and thought about the post for the 4-1000 amp using an air variable instead of a vacuum variable. This cap was supposed to have come out of a 4-1000 amp GE made. It don't say what the capacitance is. http://cgi.ebay.com/BIG-variable-loading-capacitor-for-tube-amp-4-1000A_W0QQitemZ5795970024QQcategoryZ48700QQrdZ1QQcmdZViewItem Best, Will