there should be more number then that. PP = New process plant, 833 = trans type, 590x short a number this is the assembly date, then 4 more numbers are the built on that date.
There are also additional numbers (partial vin) above the ones posted such as 8Bxxxxxx,
this should cover all possible dates - It is likely an Overdrive 4-spd
Day 5900 is Thursday, September 22, 1977
Day 5909 is Saturday, October 1, 1977
