Converting a bug to IRS is do able but takes a lot of sourcing of components. Likely donors include: the odd imported bug
the type three automatic and the Porsche 924/944
The type three is probably the easiest to source but only was available as an automatic and only in 69 one sideshaft is also longer than the other.
The 924 uses the same trailing arms and axles and are fairly common though at a price.
The type threes trailing arm brackets is also easy to remove and attach to a bug chassis although aftermarket brackets are relatively cheap.
The main problem is finding a gearbox
Luckily VW imported the Brazilia bus and supplied us with IRS boxes
Those buses came with an odball rear suspension using universal joints and reduction boxes.
Changing them to bug cvs is doable using an old 73-80 Passat box as a donor. Ifound at least two versions of the Brazilia box one with a small passat style dif and another with a regular beetle sized diff. dont forget that due to the reduction boxes the bus gearbox has the crownwheel on the opposite side of a beetle just correct when assembling otherwise you will have four reverse gears and one forward.
