I have a '79 Princeton Reverb. It is fabulous... It has everything Fender..... It uses a 5U4 Rectifier tube, which is good,... because the earliest of the Princeton Revs used the GZ-34, aka 5AR4, which are 'much more' expensive as NOS. The old USA made 5U4's are still cheap, and last 'forever'. They sound the best in my amp. Very Bluesy..