Roy,
Yellow R31 has a rb30/25, r33 gearbox with r33 gtr rear subframe/suspension. S14 front suspension with Harrop front brakes and standard rear calipers. Have only done three race meetings so far, have a list of things to do improve/change things. The car you may of seen on the 31 forums is not this car, but one that looks very similar. Both cars were built about the same time. Mine is in Tas the other I believe is in Vic. The spoiler came on the damaged car that I bought, so sorry cant help with sourcing another one.