Thanks Stenno,
I have a MA70 LSD center with 3.5:1 gears. So sweet on that count. GT4 axles are 26mm so sounds like upgrading is worth it.
Basically i'm trying to decide whether to just fit the centre and some form of modded axle to the GT4 cradle or get a whole Supra cradle and mod that to suit the GT4 body. pros and cons for both options but just modding the shafts always leaves me with an obvious weak point ....either at a CV or a spline.