Sorry for digging up an old thread.
Did you parts swap the white thighs onto an LG?
If so, how did you go about getting the legs off at the knee joint? It looks like a big flat headed pin, presumably that's s gotta come out?

 

This is still the absolute best main line ultra Magnus

 

These last few years finally brought some surprisingly fun, fantastic, & faithful figures of the G1 season 3 cast. Siege/trilogy/kingdom Ultra Magnus did not satisfy but Combiner Wars Magnus did! Glad I found one MIB for less than $55 on eBay after about a year of searching & am so happy to have the '86 Autobots of my favorite season practically completed with this guy! (Might get SS'86 Wheelie, the Universe 2 one, or both.
My season 3 autobots are:
Kingdom Rodimus Prime, Studio Series '86 Blurr, Kup & Wreck-Gar, Earthrise Sky Lynx, Combiner Wars Ultra Magnus, & Thrilling 30 Springer & Arcee.

Big size, mostly solid joints, & iconic looks abound in this Magnus.

Some mighty Autobot subcommanders, at least one of which has trouble getting along. Here he is compared to SS'86 Grimlock & Legacy Blaster.


And finally, my recent first time I put my figures of G1 Wreckers together! They are Legacy Bulkhead, Cyberverse Whirl & Rack'n'Ruin, Magnus, T30 Springer, & Generations (2010) Sgt. Kup. Loving the blue & green on display & how Magnus is the bluest!