People swap engines or transmissions for several reasons not only because they failed. Not sure if I misunderstood you but you will be responsible for the Inspection, not them, they just want to agree to take it. And for the price they paid, I have no idea how or if you can find out, but regardless, I don't see it as a good strategy since they have already their margins. Just offer them something and go from there.
"If everything seems under control, you're just not going fast enough"
River City Bimmers BMW CCA
2005 X3 3.0i
ZPP, Htd seats, Htd strng, Black Sapphire on Terracotta. (08/2008-Current)
M3 Coupe, Steel Gray Metallic on black leather, HK, three pedals.(01/2015-Current)