Not every 8HP shares a gear ratio set, and the differences sit almost entirely in first and second gear. What 4.714 vs 5.000 vs 5.500 first gears actually change, and how to pick a differential around them.
Same family number, different transmission. Bellhousings, output flanges, converters, oil pans and coolers all vary by OEM - and each one changes what your 8HP swap needs.
Why the converter in your donor 8HP may be wrong for your engine - stall speed, diesel versus petrol converters, lockup strategy, and why CAN torque reporting decides clutch pack life.