Hi Kallen and Bill
Yes I totaly agree how ever my certifying engineer will only certify the leaf spring axel not the coil as the lamination modification is not a Nissan job so would need to find another engineer to certify before lamination.
Other wise it's find a complete rear leaf spring assembly from the wreckers and then cary out the mod under the engineers supervision to get the upgrade.
He has agreed to this so looks like the way to go as the only other way is 6X4 and as I'm 7.2m long now I definitely don't want that (how ever a GVM of 4.9t and 3 sets of disc brakes makes it atractive)
Regards
Joe