trans is slippin
 

i have an '87 S10 Blazer Sport w/ an automatic trans, i don't know why but for some reason my trans slips in over drive but not in any other gear, drive, second, first, and reverse are all fine can some one please help me!!!!

RE: trans is slippin
 

Take it to a tranny shop. Post up what they tell ya.

It could be:
the governor,
oil pump assembly,
valve body assembly,
2-4 servo,
3/4 accumulator assembly,
input housing assembly, or 2-4 band assemble.

Take it to a tranny shop or your favorite GM dealer to gt it diagnosed. Depending on your skills and comfort level, you might be able to some or all of it.