I need a "Silicon Power Cube" which I believe is just a couple of SCR's,
potted, on a heat sink. Looks like this:

http://i4.photobucket.com/albums/y129/filmteknik/misc/cube1.jpg
http://i4.photobucket.com/albums/y129/filmteknik/misc/cube2.jpg

One side says 8506. The other has a sticker that says M4042. No
manufacturer name but searching around I see similar items made by Reliance
but I can't cross reference from the numbers I have. It's out of a light
dimmer that is rated to handle up to 35A at (no spam) 120V. My application is only
pulling about 10A so any similar device 15A and up would be fine. I know I
can subsitute other SCR's but that means reworking the heat sink etc. and
I'd rather replace it in kind.

BTW, I came across a RELIANCE 701819-9X which looks the same except for
markings and has two extra spade connectors where my device has spaces for
them. I don't know if that would work as I'm trying to find a spec sheet
to find out what that actually is. I think some Reliance "Power Cubes" may
be rectifiers.

Steve,
I think the Silicon Power Cube brand has become absorbed through a
series of acquisitions and mergers into the Crydom brand.
Your pictures show what looks like a dual SCR module. From your
description of the application, I'll bet that the Crydom B551SE-2T or
B561SE-2T (or equivalents) will work for you. The datasheet is at
http://www.datasheetarchive.com/pdf/802496.pdf.
Newark lists them as nonstocked items, but will drop-ship from the
manufacturer.
http://www.newark.com/72M7087/supplier-direct-ship/product.us0?sku=CRYD
OM-B551SE-2T&_requestid=89444. Digikey lists them online at
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=B551SE-2T
-ND but shows no stock. Don't know if they will drop-ship. You'll
have to ask.

Cheers!!!!!