All the common turbos... Turbonetics T-Series.. Sound Performance SP Series.. Innovative T Series.. Garrett GT series.. Greddy T78/T88... they all fit the standard T04 flange found on all common headers, including the Turbonetics/Toyomoto/PHR/DirectedEngineering cast manifold, HKS Header, Greddy Header, Sound Performance Header, etc..
Hope this answers your question.
BTW in the past I've heard a LOT of speculation about the Greddy T78/T88 flange being a different Mitsubishi flange and not bolting up to the Garrett T04 flange. I thought it was true till I saw with my own eyes a P-Trim Turbonetics exhaust housing bolt right up to a T78 header on a friend's car over at CTC.
So you know, a on-center housing will change the position of the turbo when compared to a tangential (much more common) housing. They both bolt onto the same flange, but the compressor side will end up being about a 1" difference in position because of the shape of the turbine housing.
The downpipe is trickier. There is the most common "V-band" which SP turbos and Turbonetics use. Most Garret tangential housings use this discharge type.
On-Centers turbines use a circular 4 bolt discharge.
Greddy and HKS use their own square 4 bolt flange.
You can have the downpipe modified cheaply though. For instance if you take a Greddy downpipe, cut the square flange off the very end, and weld on a $20 v-band lip, you could run a Turbonetics or SP turbo on a Greddy T78 kit...minus the T78.
Note...the above discharge types are not ALWAYS true. You put a circular 4 bolt flange on a tangential housing, some housings have a "slip on" discharge that allows you to put your choice of discharge types. This is done rarely (seldom there is a reason to), but CAN BE.