8 3/4 rear question

I have an 8 3/4 suregrip 3.91 gears in a 489 center section in my car. Theres a guy nearby with a 8 3/4 open 2.73 gears 741 center section he wants to sell. I'm thinking of picking it up for highway trips and want to know, is all I have to do is switch the center sections and my axles will fit both centers, or is there any differences in the 489 and the 741 that I'll have to take into consideration? Thanks Mike