Late model, rear wheel drive vehicles, in general, the bearing design used most is a straight roller. The bearing rollers run directly on the axle shaft. Bearing and seal life can vary. Shaft life usually is 100K. This design is used on some 3/4 ton vans and Chevy Suburbans. Rollers have great radial load capacity but zero thrust load carrying capability. Cheap, simple design. My '21 Ford has straight roller rear wheel bearings that run directly on the axle shafts - - -. IMHO closing a bearing off in it's own clean, controlled environment is not a bad concept. If contamination gets in, of course, the bearing will be compromised. Bearing life based on fatigue always applies. I had a Chrysler rear wheel Timken brand tapered bearing fail due to a factory defect gas pocket. This happened about 28 years ago. Front wheel bearings (tapered roller) on medium and HD vehicles use oil seals and run in gear oil and not grease. And, you will find that a conrad type ball bearing for a given shaft size will have a higher radial load rating than will a tapered roller bearing (like is used in vehicle wheel bearings) fitting the same shaft size. Some FWD cars use angular contact ball bearings on the front but I think separable inner race ball bearings of the type used in GM cars 40+ years ago died a long time ago in favor of the more reliable tapered roller bearing design. Warren Anderson Sedona,AZ