I have the same type WD hitch but just a different brand. These are a trunnion type hitch. The bars create friction on the L brackets as sway control.
Great WD hitch with sway control for my 10k gvwr car hauler
Mine came with a special pry bar. Go to that hitch mfg web and see how it works.
The bars are very stiff and need to use the tongue jack to raise the trailer and truck to get the bars close enough to muscle them in place.
Lots of you tubes shows how its done.
I find once my trailer is hooked up I back the trucks rear tires up on a ramp. This also raises the bars which eliminates much of the jacking....plus it gives more ground room to use the hitch mfg pry bar.
Or some folks make a hard left turn to get the left bar in place then a hard right turn for that side.
Check out the you tubes and the hitch mfg videos.
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides