msbrown79......Lube the top nut with WD40 or something similar. Put a box end wrench on the top nut and then use a large pair of Channelocks to twist the upper shock housing. The wrench will spin against the frame and hold while you twist the housing.
Usually, you can tighten to about 90% with your hands and use a strap wrench or something similar to twist the new shock tight.
I've done two RR8R's this way.
Don & Mary
2014 Newmar Dutch Star - All Electric - 450 ISL
2016 GMC Canyon 4WD Crew Cab