My truck (original 4 speed) has the crossmember. Well, my garage has the crossmember. I took it out to replace the rear transmission mount rubber (it bolts in) and never put it back in because the new mount didn't quite fit. I haven't noticed any differance with or without it. I suppose it adds some strength to the drivetrain where the U-joint housing has the potential to be tweaked by the torque tube moving around when hitting bumps but I have had some heavy loads in the truck on bumpy roads and the shift lever doesn't move around much and the motor mounts seem stable. Since it seems to have been discontinued later I think you are probably ok to remove it.
