Remember that FMIC bought Guild in 1995, and the Pilot was discontinued then so there aren't any "post Fender" Pilots. Actually, Guild's distribution just before FMIC bought the company was so sparse and the company was in pretty tough straits that I think the Pilot was actually no longer in production before FMIC took over.
I was a Guild dealer (Fender, Gibson, Ovation, Takamine, Washburn, G&L, Yamaha, etc. as well) from '77-'88. The Pilot was the best bass deal out there when they came out. Slim neck (even though I like big fat Precision necks personally, the thin neck was more sellable), active EMGs, solid bridge, and light weight when the biggest contenders were Fenders that tended to be very heavy and only one model, a Precision, had active electronics or the G&L L-2000e or the struggling (at the time) Music Man StingRay. It was decidedly NON-Fenderish and appealed to a LOT of different folks. It was what a lot of people wanted without having to buy a new bass and modify it. It certainly helped that Guild started the Hartke distribution and many ads featured Darryl Jones who played a Pilot with Sting's first non-Police project, and they had some promo with Jaco Pastorious featuring the Pilot and the Hartke 4x10 (I still have one of those Guild posters).
No years to avoid as has been said. There are a lot of variations so specifics can be very "fluid". Different headstocks and different bridges seem to be the most common variations within one model number. The Pros (at least all I've seen) had gold hardware and a Mighty Mite pre-amp with active bass and treble in addition to the EMG pickups. The most common Pilots had the EMG P/J with the P coils reversed and standard passive V/V/T (personally the best way to run EMG's- and that Mighty Mite pre wasn't nearly as good as the pickups without the pre was). For most of the run, you could also order them with passive PUPs (some generic ones at first, then later they used DiMarzio P/J PUPs) but hardly any dealers did.
John