External bellhousing, bearing retainer, pivot arm, slave cylinder, correct length clutch line, and correct clutch kit. Any AX-15 94+ should be external, and some 93s will be too.
And to answer two questions before they're asked;
1. NO, the BA 10/5 was never an external slave.
2. The AX-4/AX-5 external slave parts are NOT compatiable with an AX-15 (I have heard the slave itself is the same, but not 100% on that).