I found this on Ebay. Here's the balance plate you need for your 400 sb manual trans application.
hope this helps. Copy & paste.

Jim Sgrig "Piewagn"
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2471794618&category=33616


"I can go anywhere...for I am a Piewagoneer...To the Piewagon"

1966 Chevy Panel Delivery 1966 in the Gallery and more on Webshots