Don't buy your MOSFETs off eBay. Believe it or not, a lot of electrical components sold there are actually counterfeit. I never realized that counterfeiting FETs would be worth it, but apparently it is a big underground industry.
Digikey has what you need...
http://www.digikey.com/product-detail/e ... -ND/458775
Those parts will work fine.
Generally you need to replace the gate resistors as well, but if the FETs died from the transformer having a short, then the gate resistors are probably just fine.
I personally would remove all the power supply FETs, then replace only two of them (one for each primary winding on the coil. I would then power on the amp with a 12V headlight bulb inline with the B+ wire, and I would push and poke at the transformer to try to get the winding to short (if it is going to). If you short it, the 12V bulb will light up much brighter. When you narrow down the problem area of the transformer, you can push the windings apart, coat it in epoxy, and then install the remaining FETs. Now the amp will be good to go for a long time.
Got "schooled" by member shawn k on May 10th, 2011...
No longer really "in tune" with the audio industry, and probably have not been for some time.
Hands down the forum's most ignorant member...
Don't even know what Ohm's law is...