I have an Alamo Futura Reverb that I mentioned in the 'Let's See Your Alamo Amps' thread about a year ago, and I just started playing it again and have been thinking about trying another reverb tank in this thing. The stock tank, as verified by another member with same amp with the same tank, is an O.C. Electronics 'Cascade Reverberating Unit', type 251. That's all the specification it has besides a patent number. I measured the resistance and got 280 ohms at the input and 370 ohms at the output. This is a short tank, but it could easily fit a long one if I so desire, so it's the input/output impedance I need help figuring out. What can you fellas tell me?