Are the rear suspensions from a square and an L bug basically the same except that the square simply unbolts from the pan?

do You mean a squareback type 3?? Donn

[type 3 variant]

the early ones would have been swing axle [5 stud wheels]

and the later ones would be CV joint rear end [IRS]

Lee

Type 3 IRS is basically the same as Type 1 IRS, yeah.

Squarebacks had heavier torsion bars and double spring plates for carrying a load, but the parts from one will swap across to the other no probs.

My 68 auto beetle has IRS with twin side torsion plates

LEE

As Lee says, some Beetle IRS systems had double spring plates and some had single. Mine is an S bug and has single spring plates.