When I had the turbo 79 Mustang the turbo was rebuilt. I haven't see a shop, for that ,in a long time but they are out there. Custom compressor sides and so on. I had been using a blend of true synthetic and dino oil. The dino oil turned into what looked like brown or caramalized sugar granules and did a number on the shaft and bearings.
The cost of essentially new turbo was about half. They did not cost anything like what they do today with variable vanes, more than one compressor stage etc.
They can be rebuilt obviously but I would want to do it on a junk yard unit first and then still maybe buy it from the pros.
