will a 1964 jeep cj5 4cylinder engine and transmision fit in a1959 willyscj3b jeep
Sure, with modifications. The 3b has a 4 cylinder f head Hurricane motor, and so did the 64. Both had a T-90 transmission, I think. You may have to modify linkages, driveshaft lengths, some mounting hole locations, etc. But it should be a relatively easy swap.