I've ran a built Waggy D44 housing with 37 Krawlers. Full chromoly shafts, 300M U-joints, etc. I've broke two axle shafts. Both inner and outer shafts are 30 splined shafts, takes custom (rear axle) Warn hubs.
The rig was driven aggressively, weight around 4000#. Detroit Lockers. V8 powered, with automatic trans, and low geared Tcase.
Have since built a ProRock 60 to replace it. Just haven't got around to installing the new housing.
The housing itself hasn't bent, nor have I broke a ring gear, pinion gear, or the Detroit. Have damaged the Warn hubs.
My normal adage: D44s are good UP TO 37s if you drive reasonably and install good quality D44 parts.