How much does it cost to put in a 3SGTE into a 7th gen?
Not much if you are a very good fabricator and do everything by yourself.
You will also need an access to a machine shop, lift, TIG welder, and all the tools in the world you could imagine.
However, it could cost your right arm and left leg if you have someone else do it for you.
(Someone did this and it costs around $15k)