Transmission shifting at high revs

I just bought a 1983 olds 88 with a 307/4speed tranny and the you have to rev the car to about 3500 rpms before it shifts. If you shift the car manually the same thing happens. I was hoping someone might be able to tell me something other than rebuild it. The guy I bought it from said it didn't need to be rebuilt. I should mention the tranny fluid is red and doesn't smell burnt. And no it wasn't changed. Any help would be appreciated.

Check if it has a vacuum modulator or throttle press. linkage, either one of these could be a problem.