12 340 Springs with dampers

iam installing a camshaft with with .473 lift i dunno if that helps?

It helps some.. So you are just going to R&R your OEM 6 cyl springs? You may need retainers too. (been a long while since I peered at a 6 cyl..)
I believe the 6 cyl springs have a smaller spring OD as well... if so, you will have to either have your spring seats cut, or just order a new set with the same OD as your OEM springs..
I have 2 sets that are 1.440 OD and one other set. I will check in the morning...