This is the detail for a 2005 Joseph Chow upgrade to a T-9090 II that is now on eb*y. I interpreted this from one of the images in the auction, rather than link to a listing that will be gone in a month.
1) 'Upgrade wiring' to 16 AWG Hi-Q silver plated copper wires for power cord; upgrade to Wattgate plug
2) 'Upgrade wiring' between line filter
3) 'Upgrade wiring' between power transformer and ac switch
4) 'Upgrade wiring' between PCBs and output jacks
5) Upgrade IF ladder PCB at position X151 with 3 150 khz IF filters
6) Upgrade four rectifier diodes to fast speed soft recovery low noise diodes
7) Upgrade C211, C317, and C318 to 47uf/16v Blackgate caps
8) Upgrade power caps to 2200uf/50v Nichicon caps
9) Remove C904, C905, C906, C924, and R901
10) Upgrade Q204, Q301, and Q311 to BurrBrown OPA2134P
11) Upgrade output jacks to Teflon RCAs
12) Align sensitivity, THD, separation, 19khz leakage, and meter calibration
Item number: 190537584412