IcePack, yes, I dimly remember that the rear axle change came later on. A German forum member had a Plus 4 Supersport with a Mazda transmission in 2011 in combination with the older Salisbury rear axle where he was able to change to 4.1 and later on even ro a 4.3 ratio. I drove his car and I remember the grinding noise or whine, but in a Morgan it was ok. That BTR axle didn't come until about 2014 when my 4/4 was built when I am right. Honestly, the 3.7 final drive is the only downside to my beloved car. It sounds crazy but I always feel like I'm in the wrong gear when driving in normal traffic or in a city.
I'm toying with the idea of putting in a Mazda MX5 NC six speed gearbox because a good used 6 speed is much cheaper than a complete new shorter rear axle when a diff ratio change is not possible.. But I need to compare the gear ratios. Somewhere I read that the first gear of the 6 speed gearbox is very short and the other gears are very similar to the 5 speed gearbox. Let's see.
One more point. In another current thread the ground clearance is discussed. DaveW has sent photos where you can see that the Mazda gearbox sticks out a lot more to the ground, he showed pics. Especially with change to 175/70/15 tyres.. Dave says that this is not the case with the slimmer Ford gearbox just in case I would also choose 175/70/15 tyres.
