I put it in through the shift tower (with the shift lever removed.)
Other people might do it an easier way.
Jeep didn't make a CJ3a in 1970.
The 1952 CJ3A body can fit on a 1971 Jeep CJ5 frame with some modifications. While the two models share similarities, the mounting points and dimensions differ, requiring adjustments to ensure proper alignment and support. Custom brackets or alterations to the body may be needed to achieve a secure fit. Overall, while it's feasible, it involves a fair amount of work to make it functional and safe.