Which overdrive transmission would be easier to install?

[vetnat]

Hi. Trans would be going into a 1961 c10, hopefully behind a 292 eventually, but currently behind a 235. I think the 7 bolt side cover Saginaw O/D is a more desirable transmission, but would a 4 bolt side cover Muncie O/D transmission be an easier fit, since it more closely resembles the three speed trans that is there now? From searches, it appears some people did not have to modify their shift linkages, drive shaft, etc, and some people did. Would either O/D transmission require some modifications, or are they bolt in? Looking at a 7 bolt Saginaw O/D, from a 1968 Chevelle apparently. Thanks.