For the most part, anything 9/xx and later will be the following model year. This is particularly true for anything mid 70's and newer. Toyota actually re-VIN'ed early Land Cruisers because they didn't sell in say 1966, so they added a new tag that called them a 1967. In the case of a 10/1985, I would without doubt consider that a 1986 model year vehicle and parts would be sourced as such. Now, there are spit model year parts (such as 60 Series T-case/driveline, etc) but 95% of the parts will be specific to the model year.
Titles are not always a solid answer as it is possible for state's to mix things up. For example, I've had to do a VIN search's on late 60's and early 70's Land Cruisers. When I fill out the paperwork, I tell them what year it is, they inspect the VIN tag to verify but it could easily be 'fudged'. As such, I've seen true 1972 model year trucks (such as a Dec 1971) model year get assigned as a 1971 on the title whereas for all purposes, its a 1972. Clear as mud?