Did you fit any of these? I'm wondering if the plastic end to the front springs, which I believe is a t6.1 thing, can be taken off so that they fit into the T5 and t6 shocks?
In case you are still wondering about the makings, I now know that both sets could be fitted to the T32 or some T30s depending on the unladen weight of the van, whether it has a tow bar, if the van has the rough road suspension package etc. The fronts are pretty much all that same colour coding format, so the top one is for an axle kerb weight (ie the empty weight, not max payload) of 1186-1235kg, the bottom one is 1286-1335kg.
On the rears there are kind of 2 main ranges of springs, the yellow ones are more standard and the grey ones are what would come with the rough road package. As far as I can tell, one difference is that the thinner, lower rate part of the spring is thinner on the standard range. I guess this is more liable to break. Also it seams that the "rough road" springs also have a thicker diameter wire in the middle, so should ramp up more. The empty weight range for 4x yellow is 767-812kg, which would be the same as for 4x grey. 3x grey is designed for 721-766kg, but could well sit higher than the 4x yellow.
I used to work for marzocchi bike suspension in a past life, and I remember vaguely about having to get the lower rate (thinner) part of the spring the correct rate for the normal payload, otherwise, if you have a higher normal payload the lower rate part of the spring just spends it's whole life compressed, and the first part of the suspension stroke that you experience is mainly the higher spring rate. I believe this is why they have two different ranges of springs with progressive spring curves, rather than just one simple one. My guess is that 4x yellow and 4x grey will both carry the full T32 payload, and are both designed to take the same empty weight on the lower rate of their spring curves to be more supple, but the grey would ramp up more and sit higher at max payload.
