Never had such problems..

I always dropped new ones purchased at Autozone on my car. They drop shipped them from a GM warehouse. I always used straight mineral oil- none of this synthetic stuff. You can purchase it at Napa still.
Some say the oil feed for the front brg must be rotated. You can buy a seal kit if you want to do that. Never had the sealing rings leak= perhaps the rear of your hose needs attention. Make sure all the line clamps are correctly there.
The aftermarket rebuilds tend to grenade in a short time.

The BIG question is HOW are you flushing the system and what hoses do you replace. There is a lot of metal when an R4 dies- I suspect you have bits left in the system. I'd add a screen filter and you need a professional power flushing and some component replacement to get back to a reliable system.

M