Stuck in 3rd

It's a 3-speed manual transmission that I assume is factory as I don't recall my Dad (who I inherited it from) ever mentioning that he had any issues with it. The car was only 2 years old when be bought it in 1974. Now it has just over 60,000 miles on it. In the 2 years I've had it the only problems I've had is a hole in the gas and the power steering went out on me as stated above. Even now with the gear issue I can go outside and twist the key and it'll fire right up.

Again, I really appreciate these and future responses.