I have seen some people ask about putting a 120" rMotion in place of a 120" sc5 but havnt seen any real info on dooing this. I have pondered it for the last 2 years and now went forward dooing so. The wifes 2012 TNT sc5 tunnel was equipped with a PCX-rMotion race skid the last 2 seasons. It was a big improvement over the SC5 in the chatter and rough terain and is an easy bolt in deal unlike the consumer Rmotion. I never thought this would be very hard to do but honestly didnt think it would be this easy either.
I did a write up on the sc3 to sc4 conversion several years ago and it seemed to light a fire in people even today to do so on their rev's. That project has alot more room for error than this one here. With the SC5 to RM swap I got looking at the rivet layout on the tunnels and front arm plated area between the 2 sleds and it became very obvious of the pattern between the 2 sleds. BRP used the same plate where the front arm area is on either side of the tunnel but utilized different holes for the rmotion or sc5 and even the tmotion when i compare all these in the shop. its all of matter of which hole you choose, no front arm measuring required to drill the hole, the blank is already there.
With regard to the front arm hole relocation. You will find an oval shaped plate inside the tunnel which will get removed via 2 hardened rivets and relocated to the new holes. these "blanks" as i call them are recess' in the plate not used. go look at your sled and you will see what i am talking about.
The rear arm bracket on the sc5 i didnt feel comfortable reusing as the skid bolt hole for the rmotion is farther forward of the centerline of the highest rivet in the upside down V pattern at the rear of the tunnel. the sc5 rear skid bolt is on center of that V pattern. if we were to drill a new hole 1/2" or so ahead of the existing i would think that compromises the strength of the hole. sure, you could fill the hole, grind flush, etc if you are good with aluminum welding or plate it for strength (outside-face) and use a longer rear arm bolt? OR, just spend 20 or so per bracket from an RM 120 sled and have a clean install for the next guy (my idea).
SO, get a good grinder, cutting wheel, etc and grind flush all the rivets from the inside of the tunnel and the bottom side of the running boards. some will pop out with a punch, others need a pilot hole (1/16) and drill out 3/16 after. Use quality drill bits and dont rush it or your bit will walk and egg the hole out!
Use quality black head steel rivets. I will get the shank draw of them posted here when we are done.
all holes in the rear arm V pattern in the sc5 tunnel line up with the rmotion bracket and all but one in the footbard hole pattern can be reused. plug any holes left over with rivets or those plastic tunnel darts you already see randomly on your tunnel. those can be had in many hardware store pull out bins appropriate to hole size. black plugs for $1 or so per piece.
its straight forward with some thinking and tweaking. i will have more pics when it's done tommorrow after a few dirt shocks get rebuilt and on their way.
i'll have to get a little creative plugging the old sc5 front arm hole but i have a few ideas to make that look clean. strength isnt an issue with the adjacent holes as that oval plate i mentioned earlier is on the backside of the tunnel.
for those wondering why i am dooing this? I wanted a 120 and 137 rmotion on hand for next year and already have a tmotion summit. I sold my 12 xrs last year, no 120 RM this past season to test with other than a freinds. I have some testing to do on new shocks and need all 3 sleds available. the wife gets an upgrade and I get................satisfaction 
The freeride/gade/137 rmotion would be done the same way with regard to the front hole. I have to get a sc5 gade in here to compare to my freeride 137 for rear arm bracket area. could be a similar type of install?
