The VIN 9 was the last gasp for the SBO as we knew it. Torquey for its size, when taken care of properly would net you miles of trouble-free driving. VIN 9 did have the better balancer as mentioned. It was basically the same as the 350-455 balancer. But finding a VIN 9 engine in and of itself isn't a huge deal, in reality. It's considered the "better" 307 over the Y engine, but not by much. It was an engine built for emission reductions, first and foremost. Recall for those old enough, GM did NOT start to get back into the power game for real until about the time the G-bodies were going out the door. And as usual, Olds was late to the game most of the time anyway. Oldsmobile G-bodies sold because of their reasonable price, couch-like ride and perceived quality (of that time). For the VIN 9 engines, the 200-4R and 3.73 gears were utilized to band-aid for what the power plant lacked.
Besides the approximate 40 HP difference, for the 1983
H/O and early built 84 H/Os, the pulleys and belt arrangement were the same as all the other VIN Y engines up through 1988.
The later built 84 H/Os, at which VIN break I've yet to determine, came with the dual PS belt pulley where the alternator belt went to the water pump, lower pulley, and PS pulley as well. (I believe mid-January time frame, the same time they changed the horn button and sport steering wheel hub.)
The VIN 9 for 85 remained a flat tappet cam with the 5A heads, while the rest of the 307 Y engines went to the "new" roller-cam and peanut port setup with the 7A heads.
The ECM PROM chip was different, and the carburetor did not have a stop on the carb secondaries which allowed full opening. Camshaft and springs were different (flat tappet valve springs were stiffer, but same p/n as the 350 diesel), and the distributor did not have a thrust washer under the gear. Although 83
H/O had a different p/n intake and carb, in 84 and 85, the VIN engines were identical top to bottom.
In 1986, the VIN 9 went to roller cam, and again, identical top to bottom for the 87 model year, even using the same carb p/n. They also used the VIN 9 307 in some Cadillacs as well beyond 87.
