Hi Ralph,
sorry about the lack of responses, may just be none for sale though! Do a search on here and you might find some info for it . I'd be trying places like Vintage Suzuki and Ebay USA etc as your best source, SOMEONE on here will be able to confirm what they are using if you do enough looking though, have a look at the 4675/500 conrod post, i just added dimensions for both those, see how close they are, you can use (apparently) the Ktm rod in them with some "mods" so might work in the 400 too ....
cheers,
Kt