So, please forgive my lack of knowledge... but how would I determine if I could mount these on my w123, or, what modifications would be needed to be able to get it to install?

I think my current turbo is in need of some seals, and so this seems like a potential great opportunity to get a nice one in there!

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)