Images:
Front:
http://img156.imageshack.us/img156/6796/img0086uo6.jpg
Is it possible to see some pictures that clearly show the mounting details for the half height floppy drives in your XT 286?
I have two HH FDD sets which I believe came out of XT 286 PCs. One set is marked "IBM Component" with and has a YD-380 1.2Mb (p/n 62X0790) and a YD-580 360Kb (p/n 62X0789). The other set has two YD580 360Kb drives (p/n 6480174). All four drives have black plastic face plates that are 145mm wide.
This is narrower than most of the other 5.25" drives that I have seen.
More common width for half height 5.25" drives seems to be 148mm and the older full height FDDs (eg Tandon TM100) are 149mm wide.
The drive cutout in the front metal panel of my 5150/5160 chassis' is 147mm.
So if I fit a YD-580 or YD-380 into a 5150/5160 chassis, there is a visible gap on each side of the drive when viewed from the front.
In the picture of your XT 286, there appears to be a black (plastic?) trim piece fitted in that area - presumably to fill this gap.
Any pictures or info that clarify this point would be appreciated.
BTW I'd also be interested to know what FD controller your PC uses - is it an IBM part ?
Cheers.