[TenTec] 40823 Mosfet for Omni-C

[Stuart Rohre]

That was an RCA number I believe.  You might check the NTE web site, or
other replacement semiconductor lines.   There are also some companies that
picked up masks and dies for obsoleted American Semiconductor lines.   Try
Central Semiconductor, and Lansdale Semiconductor.  There may be something
on the American Micro Semiconductor site I mentioned having tutorials on
their web page.  It looked like they had some older part nos.  Have you
tried Mouser and other distributors for NOS?
72,
Stuart
K5KVH