I believe the BC-224-A is the rarest and perhaps the most collectible.

73 Greg KF5N

Subject: [MRCA] BC-224 vs BC-348

I have both, and was wondering if one or the other was more desirable from
a collector standpoint. I plan to have both working eventually, the BC-224
in the shack and the BC-348 in a mobile environment, both teamed up with
ART-13s.

Thanks,
Herb - W4BCH