See http://www.turbobuick.com/forums/showthread.php?s=&threadid=93074 for some eye-glazing info. Basically it is two steps smaller than a P trim. One step smaller is the turbine wheel used in the TE34, TA49, TE44, and TA/TE60 turbos - these use a 69 trim wheel. The P trim is a 76 trim and the O trim is a 62 trim. It should spool quickly, especially with the ball bearings, but I expect it would be pretty restrictive on the top end. You will have to use a 3 bolt to 4 bolt adaptor flange or replace the exhaust housing (more $$$). Also you didn't say what compressor wheel it has or anything about the rest of your combo (injectors, intercooler, heads), but I think I'd pass unless you get an awesome price.
