I bought a new pair in '75, after having been exposed to a pair a bass player friend of mine had. I lost one to a comparison test with a Peavey 1501, around '80.
(Salesman said the ALU dome was integral with the coil former to allow better heat conduction and dissapation, seemed to be true, but of course there's no way to center the coil from the front, which is why Peavey's have the removable magnet. I bought 4 1501's in '80, have yet to burn one out...) I ran the K's in 2530's, along with a bunch of D's, the 1501's lived in W boxes where the sealed back meant the only way out for heat was through the dome...
I just finished reconing that K-140 last year! (Note to self, do NOT use Duct tape to protect a gap for 25 years...
) I put a 2225 coil, 2226 cone & spider in it to test an idea I had about increasing the Xmax, currently in a W box taking all the punishment I can throw at it...
The other one is still original, and paired with a reconed D-140...
Mike Scott in SJ, CA