PK numbers

Im trying to ID a trans I have, I know it is a slant 6 727.
is it a lockup or no? Id look at the input and know, but the trans is still in the truck.
where can I look up PK numbers for future reference?
here is the number from the trans in question;
PK4058384 8720 7883
what can be said from this number? how much info on internal guts can be determined from this number? Factory hi stall? or low stall able to be determined from PK?
how high is "hi-stall" and how low is "low stall?...

PK numbers
Author: volaredon