I have a '77 Mark I. 100/60w, EQ, Reverb, Export power transformer, Koa cabinet with Altec 417-8H. It sounds great and is a piece of early Boogie history.
I own a 1978 Mark I head 60/100 EQ that I was foolish enough to sell to a friend (thought I needed a Triple Rectifier). Several years later the friend owed me some money and had none to pay. I happily told him that I would "take back the Boogie instead of cash." The Rectifier has since been sold and I have said that the only way the Mark I will ever leave is when they "pry it from my cold dead hands".
I have a 1978 100 watt Mark 1 (well they weren't really Mark I until Mark II came along) and have not had another amp since. Just this year I had to rewire the amp to replace a failing FETRON. This fetron was a discontinued transistor type device that was placed in some of the boogie amps of the time. Boogiebabies on this site helped me get this done. Now I have an ECC83 groove tube in V1 slot. Well it was great ... now it's even better restored to a full tube amp as boogies were to begin with. I love this amp.
In my search, trying to figure out what a fetron even was ... I found several good articles. This is a good overall example.