My Aero 5000 GTE's are getting on for 20 years of age now and still going strong (as are the Stradics of a similar vintage). I've still got an old Seaspin (late 80s) in good working condition somewhere.
The rear drag baitrunner came onto the market with the 5010, 6010 and 8010 where some basic standards were set. The reels were the first to use the worm shaft. These reels were fitted with graphite/ABS spools and had a mechanical anti-reverse.
The *10 range was then replaced by the first 5000/6000 & 8000 mechanically the same but the first to make use of the One Way Roller Bearing. The economical version of these reels was the RE range which had nylon bushes fitted instead of bearings and a single instead of double handle.
Then along came the GTE series with new and improved Worm Gear to produce layered line lay that helps to draw air under the line and lift it off the spool for better casting. These reels also feature Aluminium spools. Mechanically the 5000, 6000, 8000 and 1000 are all the same with the 5000-8000s all the same body but the 5000 a different rotor.
The GTE series had a number of ergonomic upgrades and hence the GTE - A, -B, C. All of these reels spools and parts are interchangeable. The 10000 can be used with the spools of the 6000, 8000 and 10000.
PS Oh $h1t just seen your post from sunny Kent above........