Try this? I hope this helps?
This part is good for 1,200 pounds tongue weight and 12,000 pounds trailer weight. Before we start we need to take care of a few preliminary steps, first its good to get the trailer in line at a nice level spot then take it apart and get some measurements off of it and well show you what measurements you need. The first measurements we need are on the truck itself. Were going to measure from the top of the wheel well down to the ground. The reason for these measurements is to make sure we get the truck back to its original height or as close as possible. Finally we need the coupler height with the trailer level on the ground. Just to make sure we need to measure from the ground to the top of the wheel well. On the front wheel we have 39-1/2 inches, and at the rear axle we have 41-1/2inches. from the ground to the top of the coupler we have about 23 inches.
Go ahead and write those measurements down on the blanks of your instruction sheet for reference later on. To start off the assembly we need to put the shank into the truck and put our head assembly on the back, loosely, and attach our ball. When installing our shank here, were going to do a quick estimate where its going to lay at, chances are were going to have to adjust it up or down. For now were just going to hold it in place. Were also at this point going to install our adjustment washers, well start off with six washers and we can always adjust it from there. Next well install the ball on here and to make it easier we will turn this sideways. Well install our 2-5/16 ball, which is part number 19286. Next were going to install the chains on our spring bars and we do that by putting the chain up to the spring bar, ing a u-bolt and putting some nuts on to hold it in place. When you tighten these down, you run the threads past the nut is all it takes. You just have to make sure this has plenty of movement. Now repeat for the other side. Next were going to couple up the truck and the trailer. We did leave the head assembly loose, which well tighten down as one of the last things we do. Next we install our spring bars and start getting those adjusted up. Before we install our lift lock brackets, we the tightening bolts that go in here. Sometimes the paint gets a little thick in there, so you might have to use a wrench to run them through. Really all this bolt does is hold everything in place. Optionally you can use these two bolt holes to permanently attach these to your trailer if you want, but its not a have to deal.
Now we need to position the lift lock brackets. You need to pull the spring bar up some you wont get too far, but pull chain as vertical as you can. Align the bracket with the center of the chain. At this point we can tighten the bracket down to the frame. Now well repeat for the other side. It looks like theres some cables in the way so well undo this to make room for it. Once we have the cables out of the way we can install our bracket. Now we can make the springbar chain connection. With the lift unit in the raised position, well pull on the chain and note which link is closest to the hook. Well note which one it is and go down two links and use that one for the hook up. Now well jack up the trailer on the ball pulling up the truck at the same time to take tension off and making it easier to hook up the chains. Now repeat for the other side. One thing to make note of is to make sure you have five links minimum. That way you have plenty of room for the chain to move in between turns. Next we our safety clips, then well lower the jack and let it carry the weight. Well adjust the hook up if necessary, we need to check and make sure the ride height hasnt changed that much. We need to check the opening at the fronts original uncoupled dimension and compare it to what we have now. 39-1/2 inches is the original dimension, and we have 39-1/2 still. The rear should be slightly lower, originally it was 41-1/4 and I have 39-3/4. About a half an inch which is acceptable. It looks like weve chosen the right weight distribution, now well tighten down the bolts on the head assembly. With our head bolts tightened down and our head screw tightened down, all in all were ready to tow. If the measurements didnt come out right, one thing wed have to do is remove some of the washers on the top or add some to achieve the proper tension we need. That covers it for part number 7903 the Draw-Tite weight distribution assembly for our 1200 pounds tongue weight and 12000 pounds trailer weight.