904 build. Where to get kits?

You may also find a transmission parts shop in your local area if you are in or near a fair sized city. My local neighborhood shop is a Transtar dealer, which is one of the bigger distributors of transmission parts nationwide. They have most parts in stock, and can get high performance stuff in pretty quick.

I'm not knocking the online guys, but you might find what you need in your local phone book. Besides, I'd rather support a local small business whenever possible.