I have a '88 2555 I bought new from the store I worked at that time,a few years later a clean 2550 came in on trade and it never went on the floor.the serial numbers are less than a hundred apart.I modded both to take 6550's or KT88's.run both at the same time, same chain except the 50 watt has a vintage mxr flanger in front of it.dessert island rig for sure.