It is considerably stronger. But if you're running just a 22R/RE, I wouldn't be concerned at all about running the 21 splined stuff. But if you're just thinking ahead for future upgrades then by all means do it. I'm running all 21 spline at the moment and have for the last 3.5 years without issue behind my 22R. But I'm looking to go to 23 spline stuff since I'm looking to do a 4.3L chevy swap.
