top speed would be good, seems as the CA doesnt have all that much power and manages to find 5th gear rev limiter easy enough

and anything that has half decent gear ratios will be better than the R30 box

so do you want top speed or fast take offs?

was playing around with the gearbox i got to put behind my CA today, it was originally out of a VL so its the RB 71c box. after playing aroun d with it for a bit i was comparing it to the SR turbo box that ive also got.....and the RB box is 2 inches shorter than the SR box
id heard that the skyline boxes (r31 and r32) were possibly shorter before, but no one had ever really confirmed it

so yeah, maked them about an inch longer than a 71b L series box and about 5 inches longer than a stumpy box

also round out the SR turbo boxes do infact have a bigger syncro between 1st and 2nd, and they have some other funcky linkages on the reverse/5th selector

my RB box also has the .75:1 ish 5th like the turbo box, whereas CA and non tubro SR boxes are .86:1 5th
so you can either have higher top speed, or run 4.11 gears and have the same cruising rpm in 5th as a different box with 3.7s