they are not the same

187 and 189 are 50000 counts
the 87 IV and 89 IV are mostly the same as 187 189, but it seems they had (87IV and 89IV) a bug in the 5v auto range, slugginess ??
287 289 are 60000 count sorry confused the thread

the 187 II and 189 II are mostly the same as 287 289
If i recall ''cough'' the 189 II is a 289 .... with an higher pcb and FW revision(s), same for the other models