Whatever body you want it must be marked for PTW only.
G&P makes one (same quality as stock), Prime makes lowers (hard to get and expensive) as well as uppers. There are lots of companies that make cast receivers of the same quality as stock.
If you want durability and quality, get the Prime, but a receiver set will cost you about $800, if you can get it.
Age verifier Northern Alberta
Democracy is two wolves and a sheep discussing what's for dinner.
Freedom is the wolves limping away while the sheep reloads.
Never confuse freedom with democracy.