The Bilstein 33-318950 is a single rear shock from the B8 5100 line, a monotube gas-charged damper for 4WD Ford F-150 trucks that carry about two inches of rear lift. Owners on user forums describe a rear setup of 5100s on a 2" rear lift and say the shocks were a "direct" fit. Compared with stock units, owners on user forums report that the metal housing is top notch, and the rubber boot is well fastened, while the factory units are flimsy plastic with no seal whatsoever. That gap in sealing and housing quality is the main reason to pay for this damper over a cheaper replacement.
Search terms this part targets include 33-318950 rear shock, Bilstein B8 5100 F-150 2 inch rear lift, and F-150 4WD monotube gas shock. Installation is a bolt-on job with no cutting. It's four bolts, 15mm ratchet and 18mm wrench. Owners on user forums report it took about fifteen minutes on one truck, and another reported it was less than an hour to get everything in place and adjusted. Confirm your model year and lift height before ordering, because fitment details vary between sources.
Owners on user forums report that the install instructions do not address boot orientation. Because of the monotube gas design, one owner noted that mounting rod side up or down does not change how the shock works. Another suggested orienting the printed Bilstein label so it reads from the side.
Owners on user forums report that the unit ships held partly compressed by a strap, while the factory shock is fully extended. You need to compress it a little by hand to slide the lower bolt in. Some owners cut the strap once the shock is mounted.
This is a light-to-moderate DIY job for someone comfortable with a floor jack and jack stands. Owners on user forums recommend mounting the top bolt first and then the bottom. One owner who started with the bottom could not get the top bolt in until loosening the bottom. Expect the passenger side to take more effort, since one owner found it wouldn't align with the lower mount without prying. Have a 15mm socket, an 18mm wrench, and a torque wrench for final tightening. Owners on user forums also advise re-checking the mounting bolts after the first drive.
