This seems to be 810 month here in the shop so I thought I would post some pics of all 3 of them since they are all different. I have seen all of these design differences in the past but never in 1 month! The 1st one, serial no 986201 definitely has no back and is a drop in case only and the lugs are different than 2 and 3:
The second one, serial no 1280363 has a removable back but I did not remove it. I have removed these in the past but they are VERY hard to get back on and they probably had a special press for this case back (you can see the gasket on the inside):
I also want to add that both no 1 and 2 require a special ring that goes below the tension ring in the crystal:
and a split stem so one can attach the crown without access to the back of the movement:
The third case, serial no 1403317 is different than 1 and 2 because the movement can be installed from the back:
This case has a typical movement holder ring and a cup to go on the back of that to keep everything tight in the case (no special extra dial ring). I think that Breitling finally realized that the drop in case was not such a good idea when I came to servicing the movement.
Now with all that said, I can tell how much fun it is (as in NOT) working with top loader cases. ANYTHING that needs adjustment means that the movement has to come back out. You HAVE to have a crystal compressor to install and remove the crystal as they need to be very tight to keep the movement from bouncing around. It was a industry fad that lasted for about a decade and done mostly to save money on watch case production. Breitling may have called these models "Top Time" but some watchmakers refer to this design as "Cheap Time". Personally I am really glad they did not continue with this idea!
Not sure if it is the lighting or what, but it already looks better. Gonna be a long 4-6 weeks.