Absolutely one of the coolest amps ever built! The head is raised by a sewing machine motor when you flip the toggle switch on top of the cab. Powerflex was a Jess Oliver of Ampeg fame design. He left Ampeg in 1966 and formed Oliver Sound. The Powerflex was a next-generation, more powerful (60 watt) version of the Portaflex.
Awesome, historically significant bass amp. Price is firm, there is one on eBay for almost $4K with 35 watchers so price is very fair. If you plan on offering less don't bother.