Th350 issue. All of a sudden, no 3rd gear

[jg1977c20]

sorry i forgot you cant get 3rd all the time - so when you drain the pan - it takes exactly 3.75 litres to fill it to proper level or 4quarts u.s.  thats how ive done every trans fluid change on a th350 ( double checking when hot of course ) and its never failed me you could try a drain and refill but it sounds like the 3rd gear clutches are gone which is normally how they end up going in for rebuild .