The ceramic vacuum variable in the 32XX series of ALPHA 77SX amplifiers had a Jennings UCSF - 500 - 0105 part number. Actually, the whole part number was << CSVF-500/UCSF-500-0105. The ratings were 12~500pF, @ 7.5KV. The unit is 3.5 wide and 7.88 long, and has a 0.250 diameter shaft. Hal Mandel KA1XO