outta curiosity what would a 4 speed a series box weigh. I know their light but does anyone have an exact figure?

Not a direct answer, but the FS5W60a 5-speed weighs 65 lbs about half-full of gear oil. I know cause I'm getting one ready for shipping.

There are three common 4-speeds, the 56-series (original 1200 issue) and two different B210/B310 4-speeds.

yeah i need to know the weight for freight aswell.

according to my scales, 19kg dry with mount and x-member.

Which 4-speed gearbox did you weigh?

I'm not up on all the codes on these boxes, but it was a standard 1973 1200 sedan 4 spd box.

Hey, that's only 42 pounds (19 kg). A lot lighter than the late B310 5-speed (65 pounds, 29kg with some fluid). No wonder Mario preferred the 4-speed.

Funny that a 300hp capable rx5 is as follows

eg.
Weights, inc bellhousings:

RX-5 - 25kg.
Supra - 35kg (Dellow BH).
Celica - 48kg (Alloy adaptor plate, RX-4 BH).

info from Ausrotary.com

That is fairly impressive ... how does Mazda make the tranny so light and yet so capable?

But not so funny if you realize HP has little to do with tranmission capacity. It's mainly the torque (twisting force) that a tranny has to withstand ... In other words 300hp @ 10,000 rpm results in only half the torque of 300hp @ 5,000 rpm.