source for large capacity electrolytics

The 5V rail in my Sun 2/120's PSU recently failed suddenly while the system was running. No pop, but the rail measures out around 2.5VDC. I believe I have tracked the fault down to one of a pair of 26000uF electrolytics which are in parallel across the 5V output studs. These are screw-lead, rated for 7.5V (12V surge), 85 deg. C, -10 +75% tol. They are 1.375" dia, and 2.125" tall. Mechanically, there is no room for anything even slighlty larger. Mouser stocks a part which is physically too tall---at 3.125", too tall by an inch. This is a 10V (12V surge) part. They also stock a 50V part from a different manufacturer which is even taller (>4"). There are 10V (12V surge) parts that fit, but have too low a capacitance (18000uF). There are 7.5V (9V surge) parts which will fit, but have too high a capacitance (49000uF), and I'm not totally sure how to be certain that a 9V surge rating is adequate in this application.