Collins 3-1/4" x 1-1/4" x 3/4" black aluminum heat sink for TO-3 or LEDs
http://us.ebid.net/for-sale/collins-...lack-aluminum-
heat-sink-for-to-3-or-leds-139209163.htm
This is a black finish rectangular aluminum heat sink drilled for one
TO-3 power transistor. The flat surfaces on all sides make it suitable
for any tab mount or LED device. Shaped like a hollow rectangular tube
extrusion, 3/4" x 1-1/4" and 3-1/4" long with 1/8" walls on all four
sides. The inside is 1/2" x 1". There is a 1-3/16" round hole on one
side to fit a TO-3 transistor down inside and against the inner bottom
surface. Military surplus FSN 5841-126-8662CW, Collins radio P/N 758-
0297-001. (Still in original packaging) At least 40 more available.
Contact me if you need a larger quantity.