t3 and t4 turbine housings? interchangeable?

[compression]

i have a turbo being built, but only comes with t4 turbine housing. and in 2 sizes, .58 and 1.13 . it is very hard to find an affordable t4 manifold or header, so i found that turbonetics sells a wide variety of turbine housings. wherein lies my question. are the turbine housings pretty interchangeable? or are they usually different in bolt pattern ? i know the turbo flange and the exhaust passage is slightly different , the t4 being larger. but if i can get a t3 turbine housing in like .68 or .82 something similar to that i can rock that. ill also pick up a nice turbonetics cast t3 manifold with a wastegate provision. nice sturdy , last a while and nice flow characteristics and they sell used for 250$ all day long i actually bought one and had to get a refund when i found out i can only use t4, another question, i found an adapter plate from t3 to t4 , but i kinda think that will be cutting corners , which i dont want to do. i can get a cheap adapter flange for 50$ shipped. nicely made too but would that hurt performance?

 

[GVR4592]

It depends on the turbine wheel size and what center section is being used. You'll need to find out those two things before you proceed with choosing a different turbine housing, if there's even one available for your application.