MATCO makes one, as does all the other tool trucks.EZ RED has a telescoping one. Gearwrench flex heads are fine. Their comfort grip versions are longer than the all metal handled versions. Gearwrench is moving from 84 teeth to a 90 tooth platform. I would stay away from the 120xp versions but, that's just me. napa's carlyle has a few offerings. Powerbuilt pro has long flex head ratchets. There are many options available besides the tool truck.
SK's 90 tooth flex heads seem to be plagued with quality control issues. The 3/8 flex I bought didn't flex properly, and the direction switch binds.
Proto precision series 90 tooth models are sweet but, overpriced. Ensure that if you buy Mac or Proto, that you get an updated model with the screw heads on top of the ratchet head.