late 50s early 60s 3channel motorola amplifier differences

I have 3 that have the same copper painted chassis but for some reason they changed configeration on each model, I have several preamps from same yet the knobs are are different config on all 3, they all interchange and work wih each other,they all use pp 6bq5 on bass while one uses pp el82(?), the other uses se 6bq5 on each right left channel, the 3rd uses a rectifier much smaller than the 5u4gb (dont know part number) can any one help me sort these out which one is the best,they all work perfectly I also have 2 same period consoles complete with jensen 15 center with little magnet.

List the model numbers and I'll see what I have on them.

Looking for schematics for hs816b, and hs768a I have others simular but no schematics for any of them they all sound great, would like to learn more about them, they are the 3 channel and have a great matching pre amp.