I dont own a 348 or 409.I do have a 1973 454,1984 366t.Someday I might put the 366t in my 81 chevy 4x4.When I was a teenager my nabor next door had a 66 impala ss convertible with a 409.Pretty bad ass car,except it was red.
I dont know the part #.All I know is its a 4 speed,with a itm shifter.If I remember,Ill look for the number for you.These saginaws were used in many different chevys and years.
What did it come out of?I really like the saginaw.When I bought my nova,the original saginaw had bad sinks in it,would grind alittle in every gear.All of the old timers over hear told me to leave it.They are stronger than any other tranny out there.They ran saginaws behind the bigblocks,blew apart the others,stock or not.They told me the cast iron ones are the best.