Can I use a new RDM clutch pack and housing from a new 2007 RDM assy and bolt it on to my 2005 RDM Gear Housing? The 2007 V6 AWD has a different gear ratio then my 2005 V6 AWD.

 

Start here.

https://www.gmpartsgiant.com/parts-list/2007-saturn-vue/brakes_rear_axle_propeller_shaft_wheels/differential_carrier.html

I don't know squat about rear differentials but you should be able to match up parts by number and application. many of the sites are doing away with descriptions and fitment for discontinued parts. This one still let you choose Saturn parts and has t fitting for everything including discontinued parts.

Please let us know what you find.