I know someone who owned a 4/4 4 seater that had a 3HA, but it was fitted when the 7HA it came with broke. I think the 3HA is an older +4 axle, this car will have had a 7HA from new.
The daft final drive ratio was fairly typical at the time, you could get a 4.56 one too if you wanted up to the early 70s (not sure when it ceased to be available).
I did run out of revs in top gear at an airfield sprint once, gives one bragging rights I guess to say you hit the rev limiter in top gear.
