i just removed my trans and took it apart. i am going to need a rebuilt kit but i dont think its the original trans from my 84. can someone tell me how to find out? the part number is: 8ypm-y-00570243-343A
it depends on how much deepier you go with your rebuild,someone rebuilds just clutches and gasket and seals,some others wants a total overhaul with bearings,valves,springs,drums,sun shell,planetary,solenoids,valve body assembly, apply pistons,band...Th 700r4 unit changed year by year since 1984.In 1987 it was renamed 4l60 some parts internally was changed,some valves,and solenoids,basically the same unit but there are differences,specially valve body assembly/solenoids.when you order a rebuild kit (total overhaul rebuild)you must be sure the model year your th 700r4 is.
Sonnax has a hunge selection of performance parts specially designed "to cure" traditional defective OEM parts in th 700r4-4l60,this link is for 4l60 unit ,but instructions guide let you choice the right parts for your model year,choice GM as make and 4l60 as unit