I have a 1969 Fender Bandmaster Reverb that has been converted into a small combo; obviously have no concerns with keeping this vintage. While its a pretty pleasant amp (other than you can hear the optical sensor for the tremolo) in most respects, I want it to break up later, have better tone when it does, and just that little bit more oomph. I noticed the OT was kind of small for the wattage this is pushing, so I figure that is a good place to start for a mod. I have no idea of the primary impedance, just that the output impedance is 4ohms. There are tons of OT's out there. I've heard of people putting in an OT from a bassman to get more headroom, and better breakup. I see tons of replacements offered from Mercury Magnets, Heyboer, Mojo (do they build their own?), and others, but I'm wondering which output transformer is going to give me the results I want? Up until I hit the $300 mark the cost isn't an issue, which leaves a lot of room to play.