Fn socom upper
2000 ls400 ecu location
PSA buys their components in bulk from whoever will offer them the best deal, so you may end up with a quality upper from FN and such or something that belongs on a hobby-grade AR. There are lots of tricks out there to take care of receiver slop, from the well-known Accu-Wedge to putting an O-Ring on the front pivot.
In typical BCM fashion, this 14.5 in. SOCOM Upper did not disappoint. This latest one is my second one with the MOD 1 Compensator, and I think it is my favorite rifle configuration. The Comp combined with the little extra weight to the barrel make the recoil a little smoother. If you want a 14.5 in. M4 upper, take a look at this set up.