Originally Posted by Kuromori

I do think bondo fillets would probably result in a stronger frame due to heat issues. Yet another reason for 631/853, as I don't think you can realistically or safely hit the hardening window for 4130 with the way a big fillet is done, even if you do fully wet out the filler and don't touch it. But no customer is ever going to be happy with bondo fillets any more than a customer would be happy if you glued some fake plastic lugs on before painting.