Your friend has a very rare piece of de Tomaso history. It appears to have been intended for the 1963 De Tomaso 2000 Sport.
Here is some information I gathered from this book-
The book contains this photo giving a clear view of the transaxle, and its upper structure that supports the rear shock absorbers. Comparing the book photo to your posted photo it is obvious they are essentially the same.
with the worldwide interest in de Tomaso, I think this should very likely be an auction house item, to gain the exposure needed to find the buyer that truly needs this.
if you read the text it indicates the car was never finished and eventually purchased from the factory as a basket case with hopes of returning it to historic racing. Surely the gentleman mentioned would be interested in this transaxle
I definitely would not sell it to the first buyer who shows up with any offer until more extensive research is done.
Larry