To complete the TH400-to-BBF adaptation, J.W. also offers a matching flexplate (part No. 93001) and crank spacer (part No. 80002-1) to ensure proper torque converter alignment on the input shaft. Essentially a BBF flexplate with a TH400 converter bolt-pattern, this J.W. piece is SFI certified and boasts a replaceable ring gear. It's offered in both standard- and lightweight trim, but for our straight-line application, we went with the heavier model.