[randywebb]

OK, I'm ahead of my deadline on real work, so I browsed this thread. Wow. I'm sure we could design a better gearbox today - in fact, I wish somebody would.

For some perspective, here is what contemporary magazine writers said, back in the day...

The [newly introduced 911’s] 5 speed gearbox is probably the new car’s best single feature.” – CAR & DRIVER, April 1965, p. 30.

The gear “lever remains delightful to use…” Motor, Jan. 29, 1972

The 901 transmission is a “superb five-speed gearbox… provides a ratio for every occasion…[and] requires so little physical effort that winding up and down through all five ratios… when pressing on in twisty or hilly country, is one of the most rewarding pleasures in motoring.”
-- Motor, Feb. 8, 1969

The 901 transmission “gate [is] well-defined.. and the powerful synchromesh is so utterly smooth and unobtrusive that the lever seems hardly to be attached to any mechanism. Upper changes are made as fast as the lever can be sliced through the gate….”
-- Motor, Feb. 8, 1969

The gear lever “movement is so natural, if you try to change across the gate, you’ll muff the shift.” “When other manufacturers want to [brag] their specifications often list Porsche-type baulk-ring synchromesh. The yardstick is Porsche and Porsche gear syncronisation is perfection.”
-- Wheels, July, 1969

The five speed, all synchromesh gearbox is one of this Porsche [911’s] greatest delights; it is light to operate and I find it almost impossible to change too quickly.”
-- Motor Sport, Jan. 1970

Note that only one comment (1972) dealt with the 915, and that Poohsan's issue is really with the 915 vs. a 901/911. Maybe it is that jog to get over into 3rd gear?

And, yes, you can put a 1970-71 tranny onto a 3L motor, I have one on a 3.2L motor.