I made inquiries of Mikael at cvi. He responded with the following. Seems like a lot of work unless you could verify the condtion of the donor. Might be easier to just swap out the differential, although I've never done this. Any tips on doing this - tips, required tools, musts to avoid?

The kit comprises new brackets that have to be welded on to the sedan axle
(of '67 vintage or later), so that you can mount the axle onto the existing
P220 trailing arms. You will have to take the panhard rod mounting bracket
from your current axle and weld it on to the sedan axle.

The sedan axle must of course be stripped of its existing mounting brackets
prior to welding on the new brackets.

The part of the process that requires most care is that of ensuring that
you weld on the brackets in the right position. I will try to get more
info. on this and let you know in another mail.

Best regards,

CVI Automotive>