Can't find this scr

[BillEaver-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

I just got 4 brand new scr's in huge heat sinks. .5 inch bolt hole. Single 
gate
lead with lug. Real nice and heavy duty. if I could get the spec's on these 
buggers
I would use them for my control panel. The trouble is the number that is on 
these
things is impossible to cross ref. If anyone can help me with this, the 
number is
18-5090-3     the other number is most likely a date code I think. 7439 
thanks for any help!
Denis Despins
KC6TRW