GPC has a house/store brand to manufacturer & model cross reference table on their site, but their table doesn't show either a Sears Model 50 or 583.96. They do show a Sako L46 as both a JCH 52 and a Sears 583.126, plus a Browning FN300 as a JCH 54.

I'm sure that Weaver made some of the Sears house/store brand scopes, so it is possible/probably that your Sears scope was made by Weaver in ElPaso. It looks like a nice example of a 1950s vintage mail order cataloge FN Mauser sporting rifle.

Jeff