The nylon 66 is tubular fed through the buttplate. The Mohawk brown model 77 is fed by a 5 round plastic magazine. The model 10-C is a identical copy of the MB77 with the exception of the ten round magazine. Yes it will work. The Apache 77 magazine is the same.
Since there's 7 models of the 66 and some models have variations the 66 would be more collectible. Example the 66 has a model that fires shorts only called the gallery special in Mohawk Brown. This model comes complete with shell deflector and loop for counter tie down chain. About 6500 made. Remington made a variation of that gun with black stock chrome barrel and chrome receiver cover. 2 to 4 hundred made very rare. I need that one. The 77MB around 15000 produced. 77 Apache numbers produced could go as high as 100,000.