It looks like CNH doesn't want to build the 66 size rotor and narrower 66 series components anymore, so you just get an 88 series with less power and no bin extensions (I can't imagine they changed the lower sheetmetal of the tank). If there is a significant price difference, it might be a good deal for someone wanting a 2388 and willing to install a power chip and bin extension. Of course, the 77 might also be the "lets find the cheapest parts" special (ie. bearings from bob's quality used bearings, chain from uncle chang's used bicycle chain shop, and belts by hemp belt),so it may have problems at 2388 power. my 2 cents, Pat