Ok to clear up...My original turbo WAS a T04 (specs unknown - roughly rated at 450hp ) I got gcg to convert it to a gt3540r using my original housings...you comprehend???
Below - quote by Michael Ramsay from an email.
"The GT3540R core swap is about a 6 hour job, where adaptors plates need to be welded and machined and tapped to the turbine housing, and some extensive machining and modification is required.
The GT35R Conversion - Rated between 600 & 650 using customers housings.
Kind Regards
Michael Ramsay
Internal Sales
GCG Turbochargers Australia Pty Ltd
Phone:+61 2 9708 2122
Fax:+61 2 9708 2912
www.gcg.com.au
Est 1979