727 Difference inside
Need to know the years of the transmission's first. The motor home 71 and later usually has four clutch drum and four pinion planetaries. May have a different governor to make it shift a little later. May also have a hard not flexible band and usually have a 3.8 lever. And of course, the better tail shaft housing (snap ring for bearing on the side instead of by the trans mount. If they are both 71 and later, they both have the better front pump (for wide bushing drum) that's about all I can think of off the top of my head. If you truly have a 68 transmission sell that one and keep the motor home to build! Hopefully this helps.