For now, milestone transmission can be checked. I used the shop manual and the technical book https://www.amazon.com/dp/1613253354/?tag=joeychgo-20, those pieces of literature covered almost every subject on the 904. The only thing I noticed, the author was often focused on 70 up 904s. Therefore I always double-checked with the 69 shop manual and year specific parts measurements, offered by transmission parts suppliers. I am quite happy with the endplay and curious about how it will work.