For those that are as interested as I am in these things, here's a list of ring gear diameters along with axle housing tube diameters for front and rear axle assemblies offered by the Carraro Group. I found these numbers about a year and a half ago but forgot I had them. All axles listed here are full floating type. Which one is being fitted to the Grenadier is unknown to me. Ineos may have specified a custom configuration but, other than width and spring perch attachment points, I somehow think that unlikely. Carraro's center sections appear to be cast and correspond roughly to many Dana Corporation components. They offer open, limited slip, and fully locked differentials for each size. The assemblies are sized by several other parameters including dynamic and peak load limits as well as gearing options. From smallest to largest sets they are:
185mm (7.28346") Ring Gear Diameter w/67.5mm (2.65748") Tube Diameter.
215mm (8.46457") Ring Gear Diameter w/76.1mm (2.996063") Tube Diameter.
220mm (8.66142") Ring Gear Diameter w/76.1mm (2.996063") Tube Diameter.
250mm (9.84252") Ring Gear Diameter w/88.9mm (3.5") Tube Diameter.
275mm (10.8628") Ring Gear Diameter w/101.6mm (4.0") Tube Diameter.
There is a smaller semi-floating rigid (rear) axle offered as well as two even larger ring gears/housings offered for rear/rigid configurations. Dana 44 ring gears are considered 216mm/8.5" and 226mm/8.8" for old and new style. Dana 60s are 9.75". Carraro also seems to offer some type of portal axle but I believe those to be for heavy industry.