"Jeff Urban" writes:

I would suspect it's house marked...

Yes, that would explain it. Some reseller brand. Like, buying a bike
marked "Schiwin"... but they haven't actually *made* bikes in decades,
it's actually some damn company in Taiwan, Korea, or China,
named "Kwang Lu Chin" or some such thing.

...The MUR860 looks alot like your description :

http://www.fairchildsemi.com/ds/RU%2FRURP860.pdf

8A 600V? Yep, that sounds very reasonable. (This circuit uses
+400VDC power supply, pulsed through MOSFETs to an eddy current
brake, to provide braking in a mechanical system. One of the mystery
diodes is used with cathode to switch point and anode to ground, to
eat the negative inductive spikes each time the MOSFETs turn off.)

And on looking at some data sheets, seems that "860" in diode part numbers
generally does mean 8A 600V.

... I can find diodes that can replace almost ANYTHING in a TO220
case...

These days, seems most of the world's electronics are made by Vishay
(China). Plus side, any parts you want, cheap. Down side, all the mfg jobs
are now in China. (Communist worker drones, $0.65/hr, 16hr/day, 6 days/wk.
American workers can compete with that. The phrase "Silicon Valley"
now means Shenzhen, Guang Dong, China. Sigh.)

... Can't say zzactly what they might cost ...

Prolly about a buck.

Anyway, thanks for the insiteful response, I think I have a handle
on what these diodes are now.

--
Cheers,
Robbie Hatley
lonewolf [at] well [dot] com