Just used Fweembucks to get some Amsoil synthetic for the gearbox

It's that time of year again, and those fweembucks are gonna go to waste soon, so I put 'em to good use and ordered three quarts of John C's Amsoil synthetic gear lube. Any tips for putting the new stuff in and taking the old out? First time I've changed the gear oil on my car; it's a '73 std.

Thanks

~Anthony