Tranny problems

Hey i got 85 s10 2.8l the problem i have is the tranny stays lock in overdrive it won't shift down to 3rd ,the engine just reves up high when i let off it catches back in overdrive unless i slow down then it goes into 3rd what causes that and how do i fix it

have the tranny fluid and filter changed first it that don't solve the problem then you may have valves sticking ( fluid and filter ) always the cheap way first

i change the fliter but i strain the old fluid and put it back in i was told that new fluid in an old tranny was like sand paper and would burn out the bands in it ,what do you think is this true and do you think this could be my problem, help!!!!!

I never heard that before.I'd go with new fluid.Even better would be flush,changing the fluid and filter doesn't get out all the old fluid.But thats the question,is the tranny worth the flush?Flushes can cost $$$$$$$$$$$$$$$$.

yeah well , I don't know i mean it shifts great in just regular drive it just the overdrive---the people at ammco transmision told me that but they might just want the work for themselves i'll try changing the fluid and see if that works.Thanks Alot ,Rick