Have not found a way to post pictures.. so here goes the explanation ..
1. install Unistrut as described by Sleepy post dated 7/10/10 note: even though this is not the same exact model you can still install it on the 1121.. it's slide is on the opposite side..
2. Identify refrigerator wall by the bolts under the camper, measure out approximately 2" from centerline of wall (toward the slide out) and drill a 1/2" hole through the center of the Unistrut, it should come out almost dead center on the angle Iron on the inside wall of the camper.. Then mark and install a 16" Galvanized tension tie from home depot $24.48 using a 1/2" x 3" bolt from bottom of Unistrut through floor and through tension tie, securing with washer and nut. note: you will have to cut tension tie sides slightly to clear wall and fit under wall seal plate..
drill from inside refrigerator wall to support plate and install two 3/8" x 2" bolts washers lock washers etc. All this was done without removing the siding or slide out frame! wish I could show pictures!