I am building up information for a Duratec install and came across the Mazda 5 and 6 speed rear drive boxes.
I like the idea of a 6 speed but understand Caterham use the 5 speed with the Duratec, there must be a good reason for this, so what are the ratios for both boxes?

Seem to recall, (IMS), an article on these boxes that stated that the six speed was not worth the extra dosh as the fifth and sixth gears respecively were the same ratio, or as near as dammit. Cheers Ray

6 speed boxes are considerably stronger, but are also in very short supply.

Do they not use completely different Diffs too? I'm sure I read something that suggested if you put a 6 speed where a 5 speed once sat, 6th gear would be the equivalent of 4 1/2 without changing the diff. Check your old PPC magazines, they had MX5's a few months ago. I'm sure that's where I read it.