I was just wondering if some of you guys that have put a 4 link in your truck have some reference points on the frame to measure from to get the geometry right. i am looking into a triangulated 4 link and i have a 48 f1 thanks

 

The recommended way is to have the rear end positioned by the leaf springs and position the 4 bars from the rear end to the frame.

When I did mine (triangulated 4-bar) I removed the rear end, placed it upside down and leveled it up and measured from each flange in toward the pumpkin to center the lower link brackets where I wanted them in relation to the position of the frame. I set mine so the lower links would be directly under the frame and tacked them in place on the axle tubes. Then I replaced the rear end under the truck (using the leaf springs to hold it in place) and hung the lower links from the brackets on the rear end. I put the forward brackets on the lower links with about 1/2 inch of play in the adjustment and where the brackets hit the frame I tacked them in.

Next I assembled the upper links to both brackets at each end and placed them on the rear end and against the frame. I used a piece of angle iron with some clamps to hold them in place on the frame while I measured and adjusted them to where I wanted them and then tacked them in place to the frame. I set them so the lower bars were level and the upper bars were pointed down slightly. I had to fabricate the brackets that attach to the pumpkin on the differential on one side because my 9 inch rear is not symmetrical in the placement of the pumpkin. It's not centered in the axle housing.

Mine came out so the top of the brackets on the top of the rear end is just about 1/2 inch below the bed floor so I didn't have to notch the frame or raise the bed or put a huge hole in the middle of my bed. It doesn't lay the frame but it does sit low enough for me.

Some pictures of the process are in my gallery.