a999 modification questions

A converter company can probably build you a special order converter but it may not be cheap. Might be just as cheap to build a lockup unit and just block the lockup function in the valve body. I haven't worked on the 904 series very much but wonder if it'd be possible to just replace the input shaft in the rear clutch carrier with a non lockup input shaft? 904-998-999 had some variances so you'd have to make sure and swap in a shaft that has the appropriate oiling holes.