More Transformer questions

I have a 212-65 chassis number 2475-65 build date 5-14-79. It seems to have the wrong output transformer in it.
The schematic calls for a 3-65 and it has a 5-75 in it.
I read where someone (Joe) had replaced his output transformer which was configured the same way and he said his amp sounded better.
Is this a factory screw up? Or did they run out of 3-65's one day and just put what they had in?
It sure looks like the original transformer to me.
Maybe it was changed at some point I'm not sure.
The amp is as clean as can be, though I never thought it sounded all that good.
I even changed the speakers without any improvement.
Now I'm thinking the problem could very well be the wrong transformer.
The only other component I could find that was different from stock was one of the op amps was listed as 2n4091 on the schematic and there was a 2n4092 installed.
I believe this is in the tremolo circuit and may explain why the tremolo does not work.
Any suggestions on changing out that transformer?
Could the 5-75 give the amp an overall muddy sound?
Thanks
Tim Connolly

Tim the 5-75 is ok it is a replace for the 3-65 with 10 more watts of power.
The 2n4092 is not the right part you need the 2n4091 for the tremelo. Take it out and see if it helps, does the tremelo work? Does the amp have new caps?

Hi Terry,
I put all new electrolytics in it a little while ago. In fact I have changed a bunch of components one at a time to see if I could get rid of the muddy tone and a loud hum I can't seem to find.
The amp was used by a harmonica player who gigged with it. I know he had very little trouble with it if any. He sold it to a guy who used it to sing through ?! Which in itself is a little weird.
When I got it it was and still is very clean in and out though it definately had some hours on it.
One speaker had a bad voice coil so I changed them out to Eminence Legends. The tubes were really weak so I changed them too.The reverb didn't work so I changed the tank and it still is intermittent.The tremolo didn't work and still doesn't though you can hear it oscillating in the background hiss when it is turned on. One day it actually picked up radio stations and sounded like an old AM receiver!
The amp has always had a nasty hum to it.
I've been poking around in it and trying different things to it as I become aware of them.
I'm no electronics wizard so it's pretty slow going. I should probably just yank the innards and send it to someone who knows what they're doing! Trouble is I really want to learn some of this stuff for myself! Next I may try changing the coupling caps.
Tim Connolly

Tim The 2n4092 should be taken out, it may be part of your muddy sound. It is for the tremolo only. Try a new cord on the reverb. What caps have you replaced? If you can not find a 2N4091 Email me.