Correct. Find the drive datasheet and read it. It's a pain, but like dropping a bomb from orbit, it's the only way to be sure -- without spending money.
For example, I'm currently considering these:
http://www.ebay.com/itm/110917812596?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
http://www.ebay.com/itm/130729532247?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
I found the datasheet here:
http://www.seagate.com/files/staticfiles/support/disc/manuals/enterprise/savvio/10K/100293075d.pdf
And it indicates that SCSI-2 support is built-in.
If I get them, I'll probably use them with this:
http://www.ebay.com/itm/110753860737?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
although I'm tempted to contact the seller and ask him if the termination can be set to only terminate the upper 8 bits. If the only option is to terminate the full bus, then such an adapted drive would need to go at the end of the SCSI cable, and in practice, pretty much mean that you could only use one at a time, or two if you install one internally and one externally.
If someone has found a better/less expensive SCA adapter, I'd like to know. Searching the web in general, the terminated SCA adapters I found were more expensive. I found one or two on Ebay and/or on Amazon which were cheaper and claimed to be terminated, but a close examination of the photographs revealed that there were no components on the circuit board which could be providing termination.
Anyway, I'm not sure there's any point in my buying those to hedge against the future. I have a few IDE/SCSI adapters. And a small stock of IBM 2 GB 50 pin drives (kind of loud, though). But the SCA adapter for these little SCSI drives is cheaper than the IDE/SCSI adapter was even at its cheapest.