Mikedsilva
IMHO, the gears are all interchangeable in 915 from 72 to 86. Yes, the input shaft changed but it it could be used in a later box, but I wouldn't. There were also improvements with dog teeth and sliders that should be considered if you are using early parts, but the gears are all interchangeable as sets. The pictures above are reversed. The input shaft with the sleeve touching 2nd gear is the later improved design, the photo below shows why they changed
