My 67 driver rear swap 411 for 373 0r 355s..

[zicc1835]

I have some pics and #s i will post here ...need some advice i want to take the 411 out and replace it with 373s or 355 323 i still want to be able to pull my boat out of the ramp but cruise on the highway. this truck is all original with a 4 speed stick (i believe and am being told a spicier ) 1st is definite a low hole and she gets off nice in 2nd but i am looking for 5th gear at 50 mph. So if someone can identify this for me i don't know if these #s are casting # s or part #s the SPID says its a 411 #3883379 can anyone recognize the make/model of this rear ?