rebuild kits.
Also check with your local diesel truck engine shop. I did that 15 years ago and got a Garrett master kit that included a new seal plate as well. G-Pop shop above link does not have the seal plate in their complete kit. Maybe they would add it for some more $? Also check with Limit Engineering and Precision Turbo and Engine for rebuild kits.
OR if you are interested, I have a NOS turbo from a NOS '85 crate engine that I opened the crate to sell parts to other hot air guys. If you saw one of my posts last year, I sent the other NOS '85 crate engine to a guy for his '37 jaguar hybrid. Do a search of my posts and see for yourself.
If you are interested in the NOS turbo, let me know and I will send you pics and cost.