Im looking to get a converter b ut i cant get a clear answer if the the converter has to be BOP specific or just for the th350. I have a th350 in a 69 gs with a stock flex plate. http://www.kmjent.com/cart/product.php?productid=85&cat=0&page=1
The TH350 and TH400 converters are interchangable, regardless of make. The only differences I've seen are in the flexplates. Some are drilled for only a large or small bolt pattern where the three converter lugs bolt up, some are drilled for both. Devon
Some converters also have dual-pattern mounting pads, so it wouldn't matter what the flex plate has as long as the mounting pads on the converter have both patterns. The converter you're looking at has a 10.5" bolt pattern. This should be diameter, so if your bolt holes are 5.25" from center of flex plate to the mounting hole you'll be good to go.
Get the one from JW on this Board. It is a proven product that many of us have and it comes with a lifetime warranty.