I know it doesn't answer the original question, but would suggest just welding it especially if you are on the fence about a spool or other locker. You can tack weld the spiders and side gears together with them in the carrier so they are lined up , and then pull them out and fully weld them in to basically a mini spool. After they cool down drop them back into the carrier. If you can weld it's basically a free way to test out how a spool would work and seems to hold up really good. I welded up my 14-bolt 15 years ago thinking it would be temporary until buying a Detroit...but it's still welded. A bunch of guys in our club have ran welded diffs also in everything from Toyota axles to Dana 60 and 70, etc... with no issues. If you weld up the 14FF the way I mentioned above all can always remove it down the road and replace with a locker without ruining the factory carrier.
When I first installed the welded 14FF I drove mine to the trails. First set of tires were 35" MT/R radials and didn't really notice any excessive wear on the back. After that I went to 13/38-16 TSL's that were grooved. They did wear faster on the back but I wouldn't call it extreme (at least not considering I was burning up grooved bias ply TSL's on the freeway). On average each wheelin' trip was 200 miles on pavement with a large percentage running 60-70 mph. I also regularly drove around town with that setup. Guessing I put 10,000-ish miles on that setup and the 38" TSL's still had okay tread on them when I went to bigger tires. Keep in mind that was a lot of off-road use and spinning on rocks, and you would be lucky to get 20,000 miles out of a set of those on the road before the cords started showing. I though handling was perfectly fine and never had any issues. The only thing you noticed was some tire squealing when making sharp turns in town or in a parking lot. In regards to tire wear, a friend ran a welded rear in his '78 F-250 on 42" TSL's for years and drove to the trails and the tires wore evenly front to rear, which I contribute to the lighter rear end weight on a pickup.