BH77 only has the additional seat and extension if it isn't put on an SU model. The SU model uses a seat swivel just like the B2650 did. But, if you have a cab model, you don't have a choice about the 2nd seat. That will add nearly 18 inches to the overall length, and your departure angle will suffer greatly too. If you don't have the cab, you can use the BH77 without the extension for the 2nd seat. That does require the swivel adapter under the tractor seat, though. I'm seeing some complaints about that swivel, but don't have my BH77 yet, so can't advise personally.