NP241 would be the most economical and easy to find. I wouldn't pay more than $200 for one though. Passenger side drops were used in 87-91 Chevy square bodies and drivers drop were used in 92-98 chevies. Slip yoke eliminators are around $700 last time I looked. The gears are plenty strong and the case will be fine as long as you don't smash it on a rock.