Yes, you have the original cap which can be removed; 1.5 turns sounds right too. I am going to reread your posts and think. OK - so you disconnect the vac, take a test drive, and it does not shift through all four gears. Agree with J Dean; think it is something in the guts of the transmission. Does not act like a vac problem. Sometimes these transmissions will not shift through the gears when they get warm if low on fluid but I believe you said you replaced the transmission fluid. Seems to me like it holds five or six quarts but do not quite remember. Could it be really low on fluid?