Not really.Don't you have to check the wear pattern with the paint?
Pinion depth, and backlash. And he's not changing pinion depth 'cause he's not dicking with the pinion at all. Which leaves...backlash.Isn't the pattern based on the the pinion depth?
Used gears are notoriously difficult to set-up properly when moving both the pinion and the ring gear. But he's using his original pinion, in the original housing, with the original depth and preload. And he's using the ring gear that's worn-in with that pinion, changing only the carrier and bearings. The only gear adjustment he's got to do is get the ring gear in the same position it was with the old carrier 'n' bearings; and that's done by getting the same backlash.
His difficulty will be getting carrier bearing preload, and backlash both correct. The new carrier may need different preload shims or adjustment to get the preload AND the backlash right.I doubt both carriers are exactly the same, but maybe you get lucky and get a good pattern if you swap them? Might be worthwhile to check though?