what is the end result you are looking for in your project? daily driver? canyon carver? short duration cruiser on weekends? long haul road tripper? when looking at rear suspension set ups keep in mind what else you will also have running back there. exhaust dumps behind rear axle will need space above the axle for tubing and also heat shields etc, exhaust dumps ahead of axle will need space as well and will also dump hot gasses which are mildly corrosive, the location and configuration of the fuel tank, fuel pump, inline filters etc and how those coilover shocks or air bags will fit around that and mount up at an angle that works to support the truck, if lowering you will need at least 3 inches above the axle so you may need a c-notch and that can affect the height of the bed floor, c notch should also have some sort of snubbers to stop axle from contacting the frame, the depth of rear wheels/tires and how the 4 link will accommodate that for width, will you be running a sway bar and if so will it be ahead or behind the axle and how will that fit around the other items fighting for space, will you run an adjustable 4 link so you can dial in the suspension for traction and the pinion angle or will it just be for looks and elimination of the leaf springs, will you run equal length 4 link arms or different length arms as this affects geometry and can cause binding as does the 3 bar set ups, will you run parallel bars and a panhard bar, maybe a watts link, parallel lower bars and angled upper bars with no panhard bar, will you be boxing the frame, are you looking at stiffening the frame with tubing kits later in the build? will you run heim joints or urethane bushings? lots of stuff to think about so a quick decision may cost you adjustablity, driveability etc later on.
these guys have a components and gussets/brackets etc catalogue if you wanna build your own. Canadian so USD goes further
https://welderseries.com/?gclid=EAIa...SAAEgIIM_D_BwE
http://www.how-to-build-hotrods.com/...ed-4-link.html
http://www.how-to-build-hotrods.com/tuning-4-link.html
http://www.jascoautomotive.com/4linkrearsuspension.htmh
ttps://www.motortrend.com/how-to/rear-suspension-guide/
https://www.ridetech.com/tech/4-link-tech/