Here's the story on that. I obtained several of those Frankensteined bars, along with some Aerodynics, at the Shreveport LA city auction back in the early 90s when they were converting their entire fleet to MX7000 bars. I knew they weren't original, so I checked with their city shop, and spoke at length with the shop foreman. He said there was a local police supply dealer that sold Lectric Lites and they had offered strobe conversion kits to the many departments in the area that still used those Yankee type bars. The dual sealed beam rotators in those bars had flimsy plastic gears that were notorious for going out, and apparently, many departments didn't have the funds on hand to purchase replacement bars when that happened. IMO, they could have easily cannibalized working rotators from their other bars, but I imagine the failure rate was becoming so frequent, it would be an ongoing chore. The dealer would contract out to convert the bars from rotators to strobes, but there was a different conversion setup originally offered, where freestanding strobe tubes mounting inside small clear inner optic lenses were used, with the 2 head power supply installed inside the bar. Those were the identical setups used in Pimp's favorite Lectric Lites LL300 Ranger bars. However, the strobes were not very bright since they were only single flash, so they started using independent strobe beacons instead in their later conversions. Shreveport unloaded all of their Frankensteined Yankee bars, along with some Aerodynics that had remote Visibeam spotlights on top, at that auction. I picked up around 50 of both types of bars for around $400 and did quite well with reselling them. Heck, I got $200 for just one of the Aeros from a local fire department! I still have one of the Yankee/Dietz bars that had the freestanding strobe setups.
K9vic, since you are in Ft. Worth, I'll bet your pictured blue/blue bar came from a small department in east Texas that had one of those conversions done, since Shreveport used red/blue domes on their bars. However, one of your domes looks much better than the other, so maybe it was converted from a red/blue bar. BTW, you said you got several of those bars, so do any of them have a clear front cutout and rear amber cutout in a red dome? If so, those were probably from bars that Bossier City LA used, as I never saw any other area departments with cutouts in their domes. BTW, I still have several red domes with those cutouts.