one of the 3-speeds was actually standard equipment behind the 340 from 68-73. There were two 3-speed manuals in '70, an A-903 that came in 6cyl cars, and an A-230 which came in everything from 6cyl cars up to the 383. If you have the A-230, I'd say you could give that thing some serious punishment from a 360 and be fine considering it came in cars behind a 383 at one point.